Optimize ImGui renderer: viewport culling and width caching

Large files made idle CPU spike because every frame re-measured every
line, recompiled the search regex per line, and ran full per-line
rendering work even for off-screen rows.

- Render only visible rows (with a small margin for smooth scrolling)
  and advance the layout cursor to preserve total content height.
- Hoist the search std::regex compilation out of the per-line loop.
- Cache the max line width on the renderer; reset only when the buffer
  or font changes, not on every edit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Buffer.cc

@@ -231,7 +231,9 @@ Buffer::Buffer(const Buffer &other)
 	mark_set_         = other.mark_set_;
 	mark_curx_        = other.mark_curx_;
 	mark_cury_        = other.mark_cury_;
-	// Copy syntax/highlighting flags
+	// Copy edit mode + syntax/highlighting flags
+	edit_mode_          = other.edit_mode_;
+	edit_mode_detected_ = other.edit_mode_detected_;
 	version_            = other.version_;
 	syntax_enabled_     = other.syntax_enabled_;
 	filetype_           = other.filetype_;
@@ -281,6 +283,8 @@ Buffer::operator=(const Buffer &other)
 	mark_set_         = other.mark_set_;
 	mark_curx_          = other.mark_curx_;
 	mark_cury_          = other.mark_cury_;
+	edit_mode_          = other.edit_mode_;
+	edit_mode_detected_ = other.edit_mode_detected_;
 	version_            = other.version_;
 	syntax_enabled_     = other.syntax_enabled_;
 	filetype_           = other.filetype_;
@@ -326,7 +330,9 @@ Buffer::Buffer(Buffer &&other) noexcept
 	  undo_tree_(std::move(other.undo_tree_)),
 	  undo_sys_(std::move(other.undo_sys_))
 {
-	// Move syntax/highlighting state
+	// Move edit mode + syntax/highlighting state
+	edit_mode_          = other.edit_mode_;
+	edit_mode_detected_ = other.edit_mode_detected_;
 	version_            = other.version_;
 	syntax_enabled_     = other.syntax_enabled_;
 	filetype_           = std::move(other.filetype_);
@@ -364,7 +370,9 @@ Buffer::operator=(Buffer &&other) noexcept
 	undo_tree_      = std::move(other.undo_tree_);
 	undo_sys_       = std::move(other.undo_sys_);
 
-	// Move syntax/highlighting state
+	// Move edit mode + syntax/highlighting state
+	edit_mode_          = other.edit_mode_;
+	edit_mode_detected_ = other.edit_mode_detected_;
 	version_            = other.version_;
 	syntax_enabled_     = other.syntax_enabled_;
 	filetype_           = std::move(other.filetype_);

Buffer.h

@@ -35,9 +35,12 @@
  */
 #pragma once
 
+#include <algorithm>
 #include <cstddef>
+#include <filesystem>
 #include <memory>
 #include <string>
+#include <unordered_set>
 #include <vector>
 #include <string_view>
 
@@ -48,6 +51,26 @@
 #include "Highlight.h"
 #include <mutex>
 
+// Edit mode determines which font class is used for a buffer.
+enum class EditMode { Code, Writing };
+
+// Detect edit mode from a filename's extension.
+inline EditMode
+DetectEditMode(const std::string &filename)
+{
+	std::string ext = std::filesystem::path(filename).extension().string();
+	std::transform(ext.begin(), ext.end(), ext.begin(), [](unsigned char c) {
+		return static_cast<char>(std::tolower(c));
+	});
+	static const std::unordered_set<std::string> writing_exts = {
+		".txt", ".md", ".markdown", ".rst", ".org",
+		".tex", ".adoc", ".asciidoc",
+	};
+	if (writing_exts.count(ext))
+		return EditMode::Writing;
+	return EditMode::Code;
+}
+
 // Forward declaration for swap journal integration
 namespace kte {
 class SwapRecorder;
@@ -484,6 +507,35 @@ public:
 	}
 
 
+	// Edit mode (code vs writing)
+	[[nodiscard]] EditMode GetEditMode() const
+	{
+		return edit_mode_;
+	}
+
+
+	void SetEditMode(EditMode m)
+	{
+		edit_mode_ = m;
+		edit_mode_detected_ = true;
+	}
+
+
+	void ToggleEditMode()
+	{
+		edit_mode_ = (edit_mode_ == EditMode::Code)
+			             ? EditMode::Writing
+			             : EditMode::Code;
+		edit_mode_detected_ = true;
+	}
+
+
+	[[nodiscard]] bool EditModeDetected() const
+	{
+		return edit_mode_detected_;
+	}
+
+
 	void SetSyntaxEnabled(bool on)
 	{
 		syntax_enabled_ = on;
@@ -614,6 +666,10 @@ private:
 	std::unique_ptr<struct UndoTree> undo_tree_;
 	std::unique_ptr<UndoSystem> undo_sys_;
 
+	// Edit mode (code vs writing)
+	EditMode edit_mode_ = EditMode::Code;
+	bool edit_mode_detected_ = false; // true after initial auto-detection
+
 	// Syntax/highlighting state
 	std::uint64_t version_ = 0; // increment on edits
 	bool syntax_enabled_   = true;

CLAUDE.md

@@ -0,0 +1,115 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+**kte** (Kyle's Text Editor) is a C++20 text editor with a terminal-first design (ncurses) and optional GUI frontends (ImGui via SDL2/OpenGL/Freetype, or Qt6). It uses a WordStar/VDE-style command model. The terminal editor is `kte`; the GUI editor is `kge`.
+
+## Build Commands
+
+```bash
+# Configure (from project root, build dir is "build")
+cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DBUILD_GUI=ON -DBUILD_TESTS=ON
+
+# Build everything
+cmake --build build
+
+# Build specific targets
+cmake --build build --target kte        # terminal editor
+cmake --build build --target kge        # GUI editor (requires -DBUILD_GUI=ON)
+cmake --build build --target kte_tests  # test suite
+
+# Run all tests
+cmake --build build --target kte_tests && ./build/kte_tests
+```
+
+There is no single-test runner; the test binary runs all tests. Tests use a minimal custom framework in `tests/Test.h` with `TEST()`, `ASSERT_EQ()`, `ASSERT_TRUE()`, `EXPECT_TRUE()` macros.
+
+### Key CMake Options
+
+| Flag | Default | Purpose |
+|------|---------|---------|
+| `BUILD_GUI` | ON | Build `kge` (ImGui GUI) |
+| `KTE_USE_QT` | OFF | Use Qt6 instead of ImGui for GUI |
+| `BUILD_TESTS` | ON | Build test suite |
+| `ENABLE_ASAN` | OFF | AddressSanitizer |
+| `KTE_STATIC_LINK` | OFF | Static linking (Linux only) |
+| `KTE_ENABLE_TREESITTER` | OFF | Tree-sitter syntax highlighting |
+
+### Nix
+
+`flake.nix` provides devshells: `default` (ImGui+debug tools), `terminal`, `qt`.
+
+### Docker (cross-platform Linux testing)
+
+```bash
+docker build -t kte-linux . && docker run --rm -v "$(pwd):/kte" kte-linux
+```
+
+## Architecture
+
+Three-layer design with strict frontend independence:
+
+```
+Frontend Layer (Terminal / ImGui / Qt / Test)
+  InputHandler.h, Renderer.h, Frontend.h interfaces
+        ↓
+Command Layer
+  CommandId enum → CommandRegistry → handler functions in Command.cc
+        ↓
+Core Model Layer
+  Editor → Buffer → PieceTable
+  UndoSystem (tree-based, records at PieceTable level)
+  SwapManager (crash recovery journal per buffer)
+```
+
+### Core Components
+
+- **PieceTable** (`PieceTable.h/.cc`) - Text storage. Lazy materialization; most ops work on the piece list directly. Line index and materialization caches must be invalidated on content changes.
+- **Buffer** (`Buffer.h/.cc`) - Wraps PieceTable. Prefer `GetLineView(row)` (zero-copy) or `GetLineString(row)` over `Rows()` (legacy, materializes all lines). All text mutations must go through PieceTable API (`insert_text`, `delete_text`) to ensure undo and swap recording work.
+- **Editor** (`Editor.h/.cc`) - Top-level state container. Primarily getters/setters; editing logic lives in commands.
+- **Command** (`Command.h/.cc`) - 120+ editing commands. This is the main place to add new editing operations. Register via `CommandRegistry::Register()` in `InstallDefaultCommands()`.
+- **UndoSystem/UndoTree/UndoNode** - Tree-based undo with branching. Group related ops with `buf.Undo()->BeginGroup()` / `EndGroup()`.
+- **Swap** (`Swap.h/.cc`) - Append-only crash recovery journal. Uses circuit breaker pattern for resilience. Files in `~/.local/state/kte/`.
+- **Syntax highlighting** (`syntax/`) - Pluggable per-language highlighters registered in `HighlighterRegistry`. Per-line caching with buffer version tracking.
+
+### Frontend Implementations
+
+Each frontend implements three interfaces (`Frontend.h`, `InputHandler.h`, `Renderer.h`):
+- **Terminal**: ncurses-based (always built)
+- **ImGui**: SDL2+OpenGL+Freetype (built with `-DBUILD_GUI=ON`)
+- **Qt**: Qt6 (built with `-DBUILD_GUI=ON -DKTE_USE_QT=ON`)
+- **Test**: Programmatic frontend for testing (always built, no UI deps)
+
+## Code Style
+
+- **C++20**, compiled with `-Wall -Wextra -Werror -pedantic`
+- **Clang** uses `-stdlib=libc++`
+- **Naming**: PascalCase for classes/methods, snake_case for variables, trailing underscore for private members (e.g., `pieces_`)
+- **Indentation**: Tabs
+- **Error handling**: Fallible ops use `bool func(args..., std::string &err)` pattern. Always clear `err` at start, capture `errno` immediately after syscall failure. Use EINTR-safe wrappers from `SyscallWrappers.h` instead of raw syscalls.
+- **ErrorHandler**: Centralized logging to `~/.local/state/kte/error.log` with severity levels (Info/Warning/Error/Critical).
+
+## Testing
+
+Tests live in `tests/test_*.cc`. Use `TestFrontend`/`TestInputHandler`/`TestRenderer` for integration tests that exercise the full Editor+Buffer+Command stack without UI dependencies.
+
+Key test files by area:
+- PieceTable: `test_piece_table.cc`
+- Buffer I/O: `test_buffer_io.cc`
+- Commands: `test_command_semantics.cc`
+- Search/replace: `test_search.cc`, `test_search_replace_flow.cc`
+- Undo: `test_undo.cc`
+- Swap (crash recovery): `test_swap_*.cc` (7 files)
+- Reflow: `test_reflow_paragraph.cc`, `test_reflow_indented_bullets.cc`
+- Integration: `test_daily_workflows.cc`
+
+## Important Caveats
+
+- `Buffer::Rows()` is legacy; use `GetLineView()` / `GetLineString()` in new code
+- `GetLineView()` returns a `string_view` valid only until next buffer modification
+- After editing ops, call `ensure_cursor_visible()` to update viewport
+- All source files are in the project root (no `src/` directory); tests are in `tests/`; syntax highlighters in `syntax/`; themes in `themes/`; embedded fonts in `fonts/`
+- External deps: `ext/imgui/` (Dear ImGui), `ext/tomlplusplus/` (TOML parser)
+- GUI config: `~/.config/kte/kge.toml` (TOML preferred over legacy INI)

CMakeLists.txt

@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 
 set(CMAKE_CXX_STANDARD 20)
-set(KTE_VERSION "1.7.0")
+set(KTE_VERSION "1.11.2")
 
 # Default to terminal-only build to avoid SDL/OpenGL dependency by default.
 # Enable with -DBUILD_GUI=ON when SDL2/OpenGL/Freetype are available.
@@ -14,6 +14,7 @@ set(BUILD_TESTS ON CACHE BOOL "Enable building test programs.")
 set(KTE_FONT_SIZE "18.0" CACHE STRING "Default font size for GUI")
 option(KTE_UNDO_DEBUG "Enable undo instrumentation logs" OFF)
 option(KTE_ENABLE_TREESITTER "Enable optional Tree-sitter highlighter adapter" OFF)
+option(KTE_STATIC_LINK "Enable static linking on Linux" OFF)
 
 # Optionally enable AddressSanitizer (ASan)
 option(ENABLE_ASAN "Enable AddressSanitizer for builds" OFF)
@@ -50,6 +51,7 @@ else ()
     )
     if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
         add_compile_options("-stdlib=libc++")
+        add_link_options("-stdlib=libc++")
     else ()
         # nothing special for gcc at the moment
     endif ()
@@ -204,6 +206,8 @@ set(FONT_HEADERS
         fonts/FontList.h
         fonts/B612Mono.h
         fonts/BrassMono.h
+        fonts/CrimsonPro.h
+        fonts/ETBook.h
         fonts/BrassMonoCode.h
         fonts/FiraCode.h
         fonts/Go.h
@@ -215,6 +219,7 @@ set(FONT_HEADERS
         fonts/IosevkaExtended.h
         fonts/ShareTech.h
         fonts/SpaceMono.h
+        fonts/Spectral.h
         fonts/Syne.h
         fonts/Triplicate.h
         fonts/Unispace.h
@@ -285,7 +290,7 @@ endif ()
 target_link_libraries(kte ${CURSES_LIBRARIES})
 
 # Static linking on Linux only (macOS does not support static linking of system libraries)
-if (NOT APPLE)
+if (NOT APPLE AND KTE_STATIC_LINK)
     target_link_options(kte PRIVATE -static)
 endif ()
 
@@ -326,6 +331,7 @@ if (BUILD_TESTS)
             tests/test_swap_edge_cases.cc
             tests/test_swap_recovery_prompt.cc
             tests/test_swap_cleanup.cc
+            tests/test_swap_cleanup2.cc
             tests/test_swap_git_editor.cc
             tests/test_piece_table.cc
             tests/test_search.cc
@@ -336,6 +342,8 @@ if (BUILD_TESTS)
             tests/test_visual_line_mode.cc
             tests/test_benchmarks.cc
             tests/test_migration_coverage.cc
+            tests/test_smart_newline.cc
+            tests/test_reflow_undo.cc
 
             # minimal engine sources required by Buffer
             PieceTable.cc
@@ -373,7 +381,7 @@ if (BUILD_TESTS)
     endif ()
 
     # Static linking on Linux only (macOS does not support static linking of system libraries)
-    if (NOT APPLE)
+    if (NOT APPLE AND KTE_STATIC_LINK)
         target_link_options(kte_tests PRIVATE -static)
     endif ()
 endif ()
@@ -416,7 +424,7 @@ if (BUILD_GUI)
     endif ()
 
     # Static linking on Linux only (macOS does not support static linking of system libraries)
-    if (NOT APPLE)
+    if (NOT APPLE AND KTE_STATIC_LINK)
         target_link_options(kge PRIVATE -static)
     endif ()
 

CONFIG.md

@@ -0,0 +1,116 @@
+# kge Configuration
+
+kge loads configuration from `~/.config/kte/kge.toml`. If no TOML file is
+found, it falls back to the legacy `kge.ini` format.
+
+## TOML Format
+
+```toml
+[window]
+fullscreen = false
+columns = 80
+rows = 42
+
+[font]
+# Default font and size
+name = "default"
+size = 18.0
+# Font used in code mode (monospace)
+code = "default"
+# Font used in writing mode (proportional)
+writing = "crimsonpro"
+
+[appearance]
+theme = "nord"
+# "dark" or "light" for themes with variants
+background = "dark"
+
+[editor]
+syntax = true
+```
+
+## Sections
+
+### `[window]`
+
+| Key          | Type | Default | Description                     |
+|--------------|------|---------|---------------------------------|
+| `fullscreen` | bool | false   | Start in fullscreen mode        |
+| `columns`    | int  | 80      | Initial window width in columns |
+| `rows`       | int  | 42      | Initial window height in rows   |
+
+### `[font]`
+
+| Key       | Type   | Default      | Description                              |
+|-----------|--------|--------------|------------------------------------------|
+| `name`    | string | "default"    | Default font loaded at startup           |
+| `size`    | float  | 18.0         | Font size in pixels                      |
+| `code`    | string | "default"    | Font for code mode (monospace)           |
+| `writing` | string | "crimsonpro" | Font for writing mode (proportional)     |
+
+### `[appearance]`
+
+| Key          | Type   | Default | Description                             |
+|--------------|--------|---------|-----------------------------------------|
+| `theme`      | string | "nord"  | Color theme                             |
+| `background` | string | "dark"  | Background mode: "dark" or "light"      |
+
+### `[editor]`
+
+| Key      | Type | Default | Description                  |
+|----------|------|---------|------------------------------|
+| `syntax` | bool | true    | Enable syntax highlighting   |
+
+## Edit Modes
+
+kge has two edit modes that control which font is used:
+
+- **code** — Uses the monospace font (`font.code`). Default for source files.
+- **writing** — Uses the proportional font (`font.writing`). Auto-detected
+  for `.txt`, `.md`, `.markdown`, `.rst`, `.org`, `.tex`, `.adoc`, and
+  `.asciidoc` files.
+
+Toggle with `C-k m` or `: mode [code|writing]`.
+
+## Available Fonts
+
+### Monospace
+
+b612, berkeley, berkeley-bold, brassmono, brassmono-bold, brassmonocode,
+brassmonocode-bold, fira, go, ibm, idealist, inconsolata, inconsolataex,
+iosevka, iosevkaex, sharetech, space, syne, triplicate, unispace
+
+### Proportional (Serif)
+
+crimsonpro, etbook, spectral
+
+## Available Themes
+
+amber, eink, everforest, gruvbox, kanagawa-paper, lcars, leuchtturm, nord,
+old-book, orbital, plan9, solarized, tufte, weyland-yutani, zenburn
+
+Themes with light/dark variants: eink, gruvbox, leuchtturm, old-book,
+solarized. Set `background = "light"` or use `: background light`.
+
+## Migrating from kge.ini
+
+If you have an existing `kge.ini`, kge will still read it but prints a
+notice to stderr suggesting migration. To migrate, create `kge.toml` in the
+same directory (`~/.config/kte/`) using the format above. The TOML file
+takes priority when both exist.
+
+The INI keys map to TOML as follows:
+
+| INI key       | TOML equivalent          |
+|---------------|--------------------------|
+| `fullscreen`  | `window.fullscreen`      |
+| `columns`     | `window.columns`         |
+| `rows`        | `window.rows`            |
+| `font`        | `font.name`              |
+| `font_size`   | `font.size`              |
+| `theme`       | `appearance.theme`       |
+| `background`  | `appearance.background`  |
+| `syntax`      | `editor.syntax`          |
+
+New keys `font.code` and `font.writing` have no INI equivalent (the INI
+parser accepts `code_font` and `writing_font` if needed).

Command.cc

@@ -115,6 +115,14 @@ ensure_cursor_visible(const Editor &ed, Buffer &buf)
 }
 
 
+static bool
+cmd_new_window(CommandContext &ctx)
+{
+	ctx.editor.SetNewWindowRequested(true);
+	return true;
+}
+
+
 static bool
 cmd_center_on_cursor(CommandContext &ctx)
 {
@@ -744,6 +752,8 @@ cmd_save_and_quit(CommandContext &ctx)
 		if (buf->IsFileBacked()) {
 			if (buf->Save(err)) {
 				buf->SetDirty(false);
+				if (auto *sm = ctx.editor.Swap())
+					sm->ResetJournal(*buf);
 			} else {
 				ctx.editor.SetStatus(err);
 				return false;
@@ -751,6 +761,8 @@ cmd_save_and_quit(CommandContext &ctx)
 		} else if (!buf->Filename().empty()) {
 			if (buf->SaveAs(buf->Filename(), err)) {
 				buf->SetDirty(false);
+				if (auto *sm = ctx.editor.Swap())
+					sm->ResetJournal(*buf);
 			} else {
 				ctx.editor.SetStatus(err);
 				return false;
@@ -1109,34 +1121,33 @@ cmd_theme_set_by_name(const CommandContext &ctx)
 static bool
 cmd_theme_set_by_name(CommandContext &ctx)
 {
-
 #  if defined(KTE_BUILD_GUI) && defined(KTE_USE_QT)
-// Qt GUI build: schedule theme change for frontend
+	// Qt GUI build: schedule theme change for frontend
-std::string name = ctx.arg;
+	std::string name = ctx.arg;
-// trim spaces
+	// trim spaces
-auto ltrim = [](std::string &s) {
+	auto ltrim = [](std::string &s) {
 		s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}));
-};
+	};
-auto rtrim = [](std::string &s) {
+	auto rtrim = [](std::string &s) {
 		s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}).base(), s.end());
-};
+	};
-ltrim (name);
+	ltrim(name);
-rtrim (name);
+	rtrim(name);
 	if (name.empty()) {
 		ctx.editor.SetStatus("theme: provide a name (e.g., nord, solarized-dark, gruvbox-light, eink)");
 		return true;
 	}
-kte::gThemeChangeRequest= name;
+	kte::gThemeChangeRequest = name;
-kte::gThemeChangePending=true;
+	kte::gThemeChangePending = true;
-ctx.editor.SetStatus (std::string("Theme requested: ") + name);
+	ctx.editor.SetStatus(std::string("Theme requested: ") + name);
 	return true;
 #  else
-(void) ctx;
+	(void) ctx;
-// No-op in terminal build
+	// No-op in terminal build
 	return true;
 #  endif
 }
@@ -1324,6 +1335,43 @@ cmd_font_set_size(CommandContext &ctx)
 #endif
 
 
+// Toggle edit mode (code/writing) for current buffer
+static bool
+cmd_toggle_edit_mode(const CommandContext &ctx)
+{
+	Buffer *b = ctx.editor.CurrentBuffer();
+	if (!b)
+		return false;
+
+	std::string arg = ctx.arg;
+	std::transform(arg.begin(), arg.end(), arg.begin(), [](unsigned char c) {
+		return static_cast<char>(std::tolower(c));
+	});
+	// Trim whitespace
+	auto start = arg.find_first_not_of(" \t");
+	if (start != std::string::npos)
+		arg = arg.substr(start);
+	auto end = arg.find_last_not_of(" \t");
+	if (end != std::string::npos)
+		arg = arg.substr(0, end + 1);
+
+	if (arg == "code") {
+		b->SetEditMode(EditMode::Code);
+	} else if (arg == "writing") {
+		b->SetEditMode(EditMode::Writing);
+	} else {
+		b->ToggleEditMode();
+	}
+
+	// Writing mode disables syntax highlighting; code mode re-enables it.
+	b->SetSyntaxEnabled(b->GetEditMode() == EditMode::Code);
+
+	const char *mode_str = (b->GetEditMode() == EditMode::Writing) ? "writing" : "code";
+	ctx.editor.SetStatus(std::string("Mode: ") + mode_str);
+	return true;
+}
+
+
 // Background set command (GUI, ImGui-only for now)
 #if defined(KTE_BUILD_GUI) && !defined(KTE_USE_QT)
 static bool
@@ -1346,6 +1394,10 @@ cmd_background_set(const CommandContext &ctx)
 	std::transform(mode.begin(), mode.end(), mode.begin(), [](unsigned char c) {
 		return (char) std::tolower(c);
 	});
+	if (mode.empty()) {
+		ctx.editor.SetStatus(std::string("Background: ") + kte::BackgroundModeName());
+		return true;
+	}
 	if (mode != "light" && mode != "dark") {
 		ctx.editor.SetStatus("background: expected 'light' or 'dark'");
 		return true;
@@ -1873,15 +1925,15 @@ cmd_insert_text(CommandContext &ctx)
 #endif
 					}
 					if (cmd == "font") {
-#if defined(KTE_BUILD_GUI) && defined(KTE_USE_QT)
-						// Complete against installed font families (case-insensitive prefix)
 						std::vector<std::string> cands;
-						QStringList fams       = QFontDatabase::families();
 						std::string apfx_lower = argprefix;
 						std::transform(apfx_lower.begin(), apfx_lower.end(), apfx_lower.begin(),
 						               [](unsigned char c) {
 							               return (char) std::tolower(c);
 						               });
+#if defined(KTE_BUILD_GUI) && defined(KTE_USE_QT)
+						// Qt: complete against system font families
+						QStringList fams = QFontDatabase::families();
 						for (const auto &fam: fams) {
 							std::string n      = fam.toStdString();
 							std::string nlower = n;
@@ -1892,6 +1944,13 @@ cmd_insert_text(CommandContext &ctx)
 							if (apfx_lower.empty() || nlower.rfind(apfx_lower, 0) == 0)
 								cands.push_back(n);
 						}
+#elif defined(KTE_BUILD_GUI)
+						// ImGui: complete against embedded font registry
+						for (const auto &n : kte::Fonts::FontRegistry::Instance().FontNames()) {
+							if (apfx_lower.empty() || n.rfind(apfx_lower, 0) == 0)
+								cands.push_back(n);
+						}
+#endif
 						if (cands.empty()) {
 							// no change
 						} else if (cands.size() == 1) {
@@ -1912,9 +1971,19 @@ cmd_insert_text(CommandContext &ctx)
 						}
 						ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
 						return true;
-#else
+					}
-						(void) argprefix;
+					if (cmd == "mode") {
-#endif
+						std::vector<std::string> modes = {"code", "writing"};
+						std::vector<std::string> cands;
+						for (const auto &m : modes) {
+							if (argprefix.empty() || m.rfind(argprefix, 0) == 0)
+								cands.push_back(m);
+						}
+						if (cands.size() == 1) {
+							ctx.editor.SetPromptText(cmd + std::string(" ") + cands[0]);
+						}
+						ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
+						return true;
 					}
 					// default: no special arg completion
 					ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
@@ -2255,10 +2324,8 @@ cmd_show_help(CommandContext &ctx)
 	};
 
 	auto populate_from_text = [](Buffer &b, const std::string &text) {
-		// Clear existing rows
+		// Clear existing content
-		while (b.Nrows() > 0) {
+		b.replace_all_bytes("");
-			b.delete_row(0);
-		}
 		// Parse text and insert rows
 		std::string line;
 		line.reserve(128);
@@ -2563,6 +2630,10 @@ cmd_newline(CommandContext &ctx)
 							ctx.editor.SetStatus(err);
 						} else {
 							buf->SetDirty(false);
+							if (auto *sm = ctx.editor.Swap()) {
+								sm->NotifyFilenameChanged(*buf);
+								sm->ResetJournal(*buf);
+							}
 							ctx.editor.SetStatus("Saved as " + value);
 							if (auto *u = buf->Undo())
 								u->mark_saved();
@@ -2949,6 +3020,58 @@ cmd_newline(CommandContext &ctx)
 }
 
 
+static bool
+cmd_smart_newline(CommandContext &ctx)
+{
+	Buffer *buf = ctx.editor.CurrentBuffer();
+	if (!buf) {
+		ctx.editor.SetStatus("No buffer to edit");
+		return false;
+	}
+
+	if (buf->IsReadOnly()) {
+		ctx.editor.SetStatus("Read-only buffer");
+		return true;
+	}
+
+	// Smart newline behavior: add a newline with the same indentation as the current line.
+	// Find indentation of current line
+	std::size_t y    = buf->Cury();
+	std::string line = buf->GetLineString(y);
+	std::string indent;
+	for (char c: line) {
+		if (c == ' ' || c == '\t') {
+			indent += c;
+		} else {
+			break;
+		}
+	}
+
+	// Perform standard newline first
+	if (!cmd_newline(ctx)) {
+		return false;
+	}
+
+	// Now insert the indentation at the new cursor position
+	if (!indent.empty()) {
+		std::size_t new_y = buf->Cury();
+		std::size_t new_x = buf->Curx();
+		buf->insert_text(static_cast<int>(new_y), static_cast<int>(new_x), indent);
+		buf->SetCursor(new_x + indent.size(), new_y);
+		buf->SetDirty(true);
+
+		if (auto *u = buf->Undo()) {
+			u->Begin(UndoType::Insert);
+			u->Append(indent);
+			u->commit();
+		}
+	}
+
+	ensure_cursor_visible(ctx.editor, *buf);
+	return true;
+}
+
+
 static bool
 cmd_backspace(CommandContext &ctx)
 {
@@ -4624,7 +4747,14 @@ cmd_reflow_paragraph(CommandContext &ctx)
 		new_lines.push_back("");
 
 	// Replace paragraph lines via PieceTable-backed operations
+	UndoSystem *u = buf->Undo();
 	for (std::size_t i = para_end; i + 1 > para_start; --i) {
+		if (u) {
+			buf->SetCursor(0, i);
+			u->Begin(UndoType::DeleteRow);
+			u->Append(static_cast<std::string>(buf->Rows()[i]));
+			u->commit();
+		}
 		buf->delete_row(static_cast<int>(i));
 		if (i == 0)
 			break; // prevent wrap on size_t
@@ -4633,6 +4763,12 @@ cmd_reflow_paragraph(CommandContext &ctx)
 	std::size_t insert_y = para_start;
 	for (const auto &ln: new_lines) {
 		buf->insert_row(static_cast<int>(insert_y), std::string_view(ln));
+		if (u) {
+			buf->SetCursor(0, insert_y);
+			u->Begin(UndoType::InsertRow);
+			u->Append(std::string_view(ln));
+			u->commit();
+		}
 		insert_y += 1;
 	}
 
@@ -4806,6 +4942,9 @@ InstallDefaultCommands()
 		CommandId::InsertText, "insert", "Insert text at cursor (no newlines)", cmd_insert_text, false, true
 	});
 	CommandRegistry::Register({CommandId::Newline, "newline", "Insert newline at cursor", cmd_newline});
+	CommandRegistry::Register({
+		CommandId::SmartNewline, "smart-newline", "Insert newline with auto-indent", cmd_smart_newline
+	});
 	CommandRegistry::Register({CommandId::Backspace, "backspace", "Delete char before cursor", cmd_backspace});
 	CommandRegistry::Register({CommandId::DeleteChar, "delete-char", "Delete char at cursor", cmd_delete_char});
 	CommandRegistry::Register({CommandId::KillToEOL, "kill-to-eol", "Delete to end of line", cmd_kill_to_eol});
@@ -4935,6 +5074,16 @@ InstallDefaultCommands()
 		CommandId::CenterOnCursor, "center-on-cursor", "Center viewport on current line", cmd_center_on_cursor,
 		false, false
 	});
+	// GUI: new window
+	CommandRegistry::Register({
+		CommandId::NewWindow, "new-window", "Open a new editor window (GUI only)", cmd_new_window,
+		false, false
+	});
+	// Edit mode toggle (public)
+	CommandRegistry::Register({
+		CommandId::ToggleEditMode, "mode", "Toggle or set edit mode: code|writing",
+		cmd_toggle_edit_mode, true, false
+	});
 }
 
 

Command.h

@@ -38,6 +38,7 @@ enum class CommandId {
 	// Editing
 	InsertText, // arg: text to insert at cursor (UTF-8, no newlines)
 	Newline, // insert a newline at cursor
+	SmartNewline, // insert a newline with auto-indent (Shift-Enter)
 	Backspace, // delete char before cursor (may join lines)
 	DeleteChar, // delete char at cursor (may join lines)
 	KillToEOL, // delete from cursor to end of line; if at EOL, delete newline
@@ -110,6 +111,14 @@ enum class CommandId {
 	SetOption, // generic ":set key=value" (v1: filetype=<lang>)
 	// Viewport control
 	CenterOnCursor, // center the viewport on the current cursor line (C-k k)
+	// GUI: open a new editor window sharing the same buffer list
+	NewWindow,
+	// GUI: font size controls
+	FontZoomIn,
+	FontZoomOut,
+	FontZoomReset,
+	// Edit mode (code/writing)
+	ToggleEditMode,
 };
 
 

Editor.cc

@@ -69,20 +69,22 @@ Editor::SetStatus(const std::string &message)
 Buffer *
 Editor::CurrentBuffer()
 {
-	if (buffers_.empty() || curbuf_ >= buffers_.size()) {
+	auto &bufs = Buffers();
+	if (bufs.empty() || curbuf_ >= bufs.size()) {
 		return nullptr;
 	}
-	return &buffers_[curbuf_];
+	return &bufs[curbuf_];
 }
 
 
 const Buffer *
 Editor::CurrentBuffer() const
 {
-	if (buffers_.empty() || curbuf_ >= buffers_.size()) {
+	const auto &bufs = Buffers();
+	if (bufs.empty() || curbuf_ >= bufs.size()) {
 		return nullptr;
 	}
-	return &buffers_[curbuf_];
+	return &bufs[curbuf_];
 }
 
 
@@ -117,8 +119,9 @@ Editor::DisplayNameFor(const Buffer &buf) const
 
 	// Prepare list of other buffer paths
 	std::vector<std::vector<std::filesystem::path> > others;
-	others.reserve(buffers_.size());
+	const auto &bufs = Buffers();
-	for (const auto &b: buffers_) {
+	others.reserve(bufs.size());
+	for (const auto &b: bufs) {
 		if (&b == &buf)
 			continue;
 		if (b.Filename().empty())
@@ -161,41 +164,44 @@ Editor::DisplayNameFor(const Buffer &buf) const
 std::size_t
 Editor::AddBuffer(const Buffer &buf)
 {
-	buffers_.push_back(buf);
+	auto &bufs = Buffers();
+	bufs.push_back(buf);
 	// Attach swap recorder
 	if (swap_) {
-		swap_->Attach(&buffers_.back());
+		swap_->Attach(&bufs.back());
-		buffers_.back().SetSwapRecorder(swap_->RecorderFor(&buffers_.back()));
+		bufs.back().SetSwapRecorder(swap_->RecorderFor(&bufs.back()));
 	}
-	if (buffers_.size() == 1) {
+	if (bufs.size() == 1) {
 		curbuf_ = 0;
 	}
-	return buffers_.size() - 1;
+	return bufs.size() - 1;
 }
 
 
 std::size_t
 Editor::AddBuffer(Buffer &&buf)
 {
-	buffers_.push_back(std::move(buf));
+	auto &bufs = Buffers();
+	bufs.push_back(std::move(buf));
 	if (swap_) {
-		swap_->Attach(&buffers_.back());
+		swap_->Attach(&bufs.back());
-		buffers_.back().SetSwapRecorder(swap_->RecorderFor(&buffers_.back()));
+		bufs.back().SetSwapRecorder(swap_->RecorderFor(&bufs.back()));
 	}
-	if (buffers_.size() == 1) {
+	if (bufs.size() == 1) {
 		curbuf_ = 0;
 	}
-	return buffers_.size() - 1;
+	return bufs.size() - 1;
 }
 
 
 bool
 Editor::OpenFile(const std::string &path, std::string &err)
 {
-	// If there is exactly one unnamed, empty, clean buffer, reuse it instead
+	// If the current buffer is an unnamed, empty, clean scratch buffer, reuse
-	// of creating a new one.
+	// it instead of creating a new one.
-	if (buffers_.size() == 1) {
+	auto &bufs_ref = Buffers();
-		Buffer &cur                  = buffers_[curbuf_];
+	if (!bufs_ref.empty() && curbuf_ < bufs_ref.size()) {
+		Buffer &cur                  = bufs_ref[curbuf_];
 		const bool unnamed           = cur.Filename().empty() && !cur.IsFileBacked();
 		const bool clean             = !cur.Dirty();
 		const std::size_t nrows      = cur.Nrows();
@@ -268,7 +274,7 @@ Editor::OpenFile(const std::string &path, std::string &err)
 	// Add as a new buffer and switch to it
 	std::size_t idx = AddBuffer(std::move(b));
 	if (swap_) {
-		swap_->NotifyFilenameChanged(buffers_[idx]);
+		swap_->NotifyFilenameChanged(Buffers()[idx]);
 	}
 	SwitchTo(idx);
 	// Defensive: ensure any active prompt is closed after a successful open
@@ -446,12 +452,13 @@ Editor::ProcessPendingOpens()
 bool
 Editor::SwitchTo(std::size_t index)
 {
-	if (index >= buffers_.size()) {
+	auto &bufs = Buffers();
+	if (index >= bufs.size()) {
 		return false;
 	}
 	curbuf_ = index;
 	// Robustness: ensure a valid highlighter is installed when switching buffers
-	Buffer &b = buffers_[curbuf_];
+	Buffer &b = bufs[curbuf_];
 	if (b.SyntaxEnabled()) {
 		b.EnsureHighlighter();
 		if (auto *eng = b.Highlighter()) {
@@ -478,21 +485,22 @@ Editor::SwitchTo(std::size_t index)
 bool
 Editor::CloseBuffer(std::size_t index)
 {
-	if (index >= buffers_.size()) {
+	auto &bufs = Buffers();
+	if (index >= bufs.size()) {
 		return false;
 	}
 	if (swap_) {
 		// Always remove swap file when closing a buffer on normal exit.
 		// Swap files are for crash recovery; on clean close, we don't need them.
 		// This prevents stale swap files from accumulating (e.g., when used as git editor).
-		swap_->Detach(&buffers_[index], true);
+		swap_->Detach(&bufs[index], true);
-		buffers_[index].SetSwapRecorder(nullptr);
+		bufs[index].SetSwapRecorder(nullptr);
 	}
-	buffers_.erase(buffers_.begin() + static_cast<std::ptrdiff_t>(index));
+	bufs.erase(bufs.begin() + static_cast<std::ptrdiff_t>(index));
-	if (buffers_.empty()) {
+	if (bufs.empty()) {
 		curbuf_ = 0;
-	} else if (curbuf_ >= buffers_.size()) {
+	} else if (curbuf_ >= bufs.size()) {
-		curbuf_ = buffers_.size() - 1;
+		curbuf_ = bufs.size() - 1;
 	}
 	return true;
 }
@@ -516,7 +524,12 @@ Editor::Reset()
 	// Reset close-confirm/save state
 	close_confirm_pending_ = false;
 	close_after_save_      = false;
-	buffers_.clear();
+	auto &bufs = Buffers();
+	if (swap_) {
+		for (auto &buf : bufs)
+			swap_->Detach(&buf, true);
+	}
+	bufs.clear();
 	curbuf_ = 0;
 }
 

Editor.h

@@ -246,6 +246,18 @@ public:
 	}
 
 
+	void SetNewWindowRequested(bool on)
+	{
+		new_window_requested_ = on;
+	}
+
+
+	[[nodiscard]] bool NewWindowRequested() const
+	{
+		return new_window_requested_;
+	}
+
+
 	void SetQuitConfirmPending(bool on)
 	{
 		quit_confirm_pending_ = on;
@@ -509,7 +521,7 @@ public:
 	// Buffers
 	[[nodiscard]] std::size_t BufferCount() const
 	{
-		return buffers_.size();
+		return Buffers().size();
 	}
 
 
@@ -519,6 +531,19 @@ public:
 	}
 
 
+	// Clamp curbuf_ to valid range. Call when the shared buffer list may
+	// have been modified by another editor (e.g., buffer closed in another window).
+	void ValidateBufferIndex()
+	{
+		const auto &bufs = Buffers();
+		if (bufs.empty()) {
+			curbuf_ = 0;
+		} else if (curbuf_ >= bufs.size()) {
+			curbuf_ = bufs.size() - 1;
+		}
+	}
+
+
 	Buffer *CurrentBuffer();
 
 	const Buffer *CurrentBuffer() const;
@@ -570,13 +595,22 @@ public:
 	// Direct access when needed (try to prefer methods above)
 	[[nodiscard]] const std::vector<Buffer> &Buffers() const
 	{
-		return buffers_;
+		return shared_buffers_ ? *shared_buffers_ : buffers_;
 	}
 
 
 	std::vector<Buffer> &Buffers()
 	{
-		return buffers_;
+		return shared_buffers_ ? *shared_buffers_ : buffers_;
+	}
+
+
+	// Share another editor's buffer list. When set, this editor operates on
+	// the provided vector instead of its own. Pass nullptr to detach.
+	void SetSharedBuffers(std::vector<Buffer> *shared)
+	{
+		shared_buffers_ = shared;
+		curbuf_         = 0;
 	}
 
 
@@ -628,6 +662,7 @@ private:
 	bool repeatable_   = false; // whether the next command is repeatable
 
 	std::vector<Buffer> buffers_;
+	std::vector<Buffer> *shared_buffers_ = nullptr; // if set, use this instead of buffers_
 	std::size_t curbuf_                  = 0; // index into buffers_
 
 	// Swap journaling manager (lifetime = editor)
@@ -639,6 +674,7 @@ private:
 
 	// Quit state
 	bool quit_requested_        = false;
+	bool new_window_requested_  = false;
 	bool quit_confirm_pending_  = false;
 	bool close_confirm_pending_ = false; // awaiting y/N to save-before-close
 	bool close_after_save_      = false; // if true, close buffer after successful Save/SaveAs

ErrorHandler.cc

@@ -20,6 +20,8 @@ ErrorHandler::ErrorHandler()
 				fs::create_directories(log_dir);
 			}
 			log_file_path_ = (log_dir / "error.log").string();
+			// Create the log file immediately so it exists in the state directory
+			ensure_log_file();
 		} catch (...) {
 			// If we can't create the directory, disable file logging
 			file_logging_enabled_ = false;
@@ -34,11 +36,7 @@ ErrorHandler::ErrorHandler()
 ErrorHandler::~ErrorHandler()
 {
 	std::lock_guard<std::mutex> lg(mtx_);
-	if (log_file_ &&log_file_
+	if (log_file_ && log_file_->is_open()) {
-	->
-	is_open()
-	)
-	{
 		log_file_->flush();
 		log_file_->close();
 	}
@@ -249,10 +247,7 @@ void
 ErrorHandler::ensure_log_file()
 {
 	// Must be called with mtx_ held
-	if (log_file_ &&log_file_
+	if (log_file_ && log_file_->is_open())
-	->
-	is_open()
-	)
 		return;
 
 	if (log_file_path_.empty())
@@ -313,6 +308,6 @@ std::uint64_t
 ErrorHandler::now_ns()
 {
 	using namespace std::chrono;
-	return duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count();
+	return duration_cast<nanoseconds>(system_clock::now().time_since_epoch()).count();
 }
 } // namespace kte

GUIConfig.cc

@@ -3,9 +3,29 @@
 #include <fstream>
 #include <sstream>
 #include <algorithm>
+#include <filesystem>
+#include <iostream>
 
 #include "GUIConfig.h"
 
+// toml++ for TOML config parsing
+#if defined(__clang__)
+#  pragma clang diagnostic push
+#  pragma clang diagnostic ignored "-Weverything"
+#elif defined(__GNUC__)
+#  pragma GCC diagnostic push
+#  pragma GCC diagnostic ignored "-Wall"
+#  pragma GCC diagnostic ignored "-Wextra"
+#endif
+
+#include "ext/tomlplusplus/toml.hpp"
+
+#if defined(__clang__)
+#  pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#  pragma GCC diagnostic pop
+#endif
+
 
 static void
 trim(std::string &s)
@@ -19,37 +39,124 @@ trim(std::string &s)
 
 
 static std::string
-default_config_path()
+config_dir()
 {
 	const char *home = std::getenv("HOME");
 	if (!home || !*home)
 		return {};
-	std::string path(home);
+	return std::string(home) + "/.config/kte";
-	path += "/.config/kte/kge.ini";
-	return path;
 }
 
 
 GUIConfig
 GUIConfig::Load()
 {
-	GUIConfig cfg; // defaults already set
+	GUIConfig cfg;
-	const std::string path = default_config_path();
+	std::string dir = config_dir();
+	if (dir.empty())
+		return cfg;
 
-	if (!path.empty()) {
+	// Try TOML first
-		cfg.LoadFromFile(path);
+	std::string toml_path = dir + "/kge.toml";
+	if (cfg.LoadFromTOML(toml_path))
+		return cfg;
+
+	// Fall back to legacy INI
+	std::string ini_path = dir + "/kge.ini";
+	if (cfg.LoadFromINI(ini_path)) {
+		std::cerr << "kge: loaded legacy kge.ini; consider migrating to kge.toml\n";
+		return cfg;
 	}
+
 	return cfg;
 }
 
 
 bool
-GUIConfig::LoadFromFile(const std::string &path)
+GUIConfig::LoadFromTOML(const std::string &path)
+{
+	if (!std::filesystem::exists(path))
+		return false;
+
+	toml::table tbl;
+	try {
+		tbl = toml::parse_file(path);
+	} catch (const toml::parse_error &err) {
+		std::cerr << "kge: TOML parse error in " << path << ": " << err.what() << "\n";
+		return false;
+	}
+
+	// [window]
+	if (auto win = tbl["window"].as_table()) {
+		if (auto v = (*win)["fullscreen"].value<bool>())
+			fullscreen = *v;
+		if (auto v = (*win)["columns"].value<int64_t>()) {
+			if (*v > 0) columns = static_cast<int>(*v);
+		}
+		if (auto v = (*win)["rows"].value<int64_t>()) {
+			if (*v > 0) rows = static_cast<int>(*v);
+		}
+	}
+
+	// [font]
+	bool explicit_code_font    = false;
+	bool explicit_writing_font = false;
+	if (auto sec = tbl["font"].as_table()) {
+		if (auto v = (*sec)["name"].value<std::string>())
+			font = *v;
+		if (auto v = (*sec)["size"].value<double>()) {
+			if (*v > 0.0) font_size = static_cast<float>(*v);
+		}
+		if (auto v = (*sec)["code"].value<std::string>()) {
+			code_font = *v;
+			explicit_code_font = true;
+		}
+		if (auto v = (*sec)["writing"].value<std::string>()) {
+			writing_font = *v;
+			explicit_writing_font = true;
+		}
+	}
+
+	// [appearance]
+	if (auto sec = tbl["appearance"].as_table()) {
+		if (auto v = (*sec)["theme"].value<std::string>())
+			theme = *v;
+		if (auto v = (*sec)["background"].value<std::string>()) {
+			std::string bg = *v;
+			std::transform(bg.begin(), bg.end(), bg.begin(), [](unsigned char c) {
+				return (char) std::tolower(c);
+			});
+			if (bg == "light" || bg == "dark")
+				background = bg;
+		}
+	}
+
+	// [editor]
+	if (auto sec = tbl["editor"].as_table()) {
+		if (auto v = (*sec)["syntax"].value<bool>())
+			syntax = *v;
+	}
+
+	// Default code_font to the main font if not explicitly set
+	if (!explicit_code_font)
+		code_font = font;
+	if (!explicit_writing_font && writing_font == "crimsonpro" && font != "default")
+		writing_font = font;
+
+	return true;
+}
+
+
+bool
+GUIConfig::LoadFromINI(const std::string &path)
 {
 	std::ifstream in(path);
 	if (!in.good())
 		return false;
 
+	bool explicit_code_font    = false;
+	bool explicit_writing_font = false;
+
 	std::string line;
 	while (std::getline(in, line)) {
 		// Remove comments starting with '#' or ';'
@@ -104,6 +211,12 @@ GUIConfig::LoadFromFile(const std::string &path)
 			}
 		} else if (key == "font") {
 			font = val;
+		} else if (key == "code_font") {
+			code_font = val;
+			explicit_code_font = true;
+		} else if (key == "writing_font") {
+			writing_font = val;
+			explicit_writing_font = true;
 		} else if (key == "theme") {
 			theme = val;
 		} else if (key == "background" || key == "bg") {
@@ -126,5 +239,13 @@ GUIConfig::LoadFromFile(const std::string &path)
 		}
 	}
 
+	// If code_font was not explicitly set, default it to the main font
+	// so that the edit-mode font switcher doesn't immediately switch away
+	// from the font loaded during Init.
+	if (!explicit_code_font)
+		code_font = font;
+	if (!explicit_writing_font && writing_font == "crimsonpro" && font != "default")
+		writing_font = font;
+
 	return true;
 }

GUIConfig.h

@@ -1,5 +1,7 @@
 /*
- * GUIConfig - loads simple GUI configuration from $HOME/.config/kte/kge.ini
+ * GUIConfig - loads GUI configuration from $HOME/.config/kte/kge.toml
+ *
+ * Falls back to legacy kge.ini if no TOML config is found.
  */
 #pragma once
 
@@ -22,12 +24,18 @@ public:
 	std::string background = "dark";
 
 	// Default syntax highlighting state for GUI (kge): on/off
-	// Accepts: on/off/true/false/yes/no/1/0 in the ini file.
+	bool syntax = true;
-	bool syntax = true; // default: enabled
 
-	// Load from default path: $HOME/.config/kte/kge.ini
+	// Per-mode font defaults
+	std::string code_font    = "default";
+	std::string writing_font = "crimsonpro";
+
+	// Load from default paths: try kge.toml first, fall back to kge.ini
 	static GUIConfig Load();
 
-	// Load from explicit path. Returns true if file existed and was parsed.
+	// Load from explicit TOML path. Returns true if file existed and was parsed.
-	bool LoadFromFile(const std::string &path);
+	bool LoadFromTOML(const std::string &path);
+
+	// Load from explicit INI path (legacy). Returns true if file existed and was parsed.
+	bool LoadFromINI(const std::string &path);
 };

GUITheme.h

@@ -312,7 +312,7 @@ namespace kte {
 enum class BackgroundMode { Light, Dark };
 
 // Global background mode; default to Dark to match prior defaults
-static inline auto gBackgroundMode = BackgroundMode::Dark;
+inline auto gBackgroundMode = BackgroundMode::Dark;
 
 // Basic theme identifier (kept minimal; some ids are aliases)
 enum class ThemeId {
@@ -330,11 +330,13 @@ enum class ThemeId {
 	Amber = 10,
 	WeylandYutani = 11,
 	Orbital = 12,
+	Tufte = 13,
+	Leuchtturm = 14,
 };
 
 // Current theme tracking
-static inline auto gCurrentTheme             = ThemeId::Nord;
+inline auto gCurrentTheme             = ThemeId::Nord;
-static inline std::size_t gCurrentThemeIndex = 6; // Nord index
+inline std::size_t gCurrentThemeIndex = 7; // Nord index
 
 // Forward declarations for helpers used below
 static size_t ThemeIndexFromId(ThemeId id);
@@ -372,11 +374,13 @@ BackgroundModeName()
 #include "themes/Everforest.h"
 #include "themes/KanagawaPaper.h"
 #include "themes/LCARS.h"
+#include "themes/Leuchtturm.h"
 #include "themes/OldBook.h"
 #include "themes/Amber.h"
 #include "themes/WeylandYutani.h"
 #include "themes/Zenburn.h"
 #include "themes/Orbital.h"
+#include "themes/Tufte.h"
 
 
 // Theme abstraction and registry (generalized theme system)
@@ -409,6 +413,28 @@ struct LCARSTheme final : Theme {
 	}
 };
 
+struct LeuchtturmTheme final : Theme {
+	[[nodiscard]] const char *Name() const override
+	{
+		return "leuchtturm";
+	}
+
+
+	void Apply() const override
+	{
+		if (gBackgroundMode == BackgroundMode::Dark)
+			ApplyLeuchtturmDarkTheme();
+		else
+			ApplyLeuchtturmLightTheme();
+	}
+
+
+	ThemeId Id() override
+	{
+		return ThemeId::Leuchtturm;
+	}
+};
+
 struct EverforestTheme final : Theme {
 	[[nodiscard]] const char *Name() const override
 	{
@@ -488,6 +514,28 @@ struct OrbitalTheme final : Theme {
 	}
 };
 
+struct TufteTheme final : Theme {
+	[[nodiscard]] const char *Name() const override
+	{
+		return "tufte";
+	}
+
+
+	void Apply() const override
+	{
+		if (gBackgroundMode == BackgroundMode::Dark)
+			ApplyTufteDarkTheme();
+		else
+			ApplyTufteLightTheme();
+	}
+
+
+	ThemeId Id() override
+	{
+		return ThemeId::Tufte;
+	}
+};
+
 struct ZenburnTheme final : Theme {
 	[[nodiscard]] const char *Name() const override
 	{
@@ -657,18 +705,20 @@ ThemeRegistry()
 	static std::vector<std::unique_ptr<Theme> > reg;
 	if (reg.empty()) {
 		// Alphabetical by canonical name:
-		// amber, eink, everforest, gruvbox, kanagawa-paper, lcars, nord, old-book, orbital, plan9, solarized, weyland-yutani, zenburn
+		// amber, eink, everforest, gruvbox, kanagawa-paper, lcars, leuchtturm, nord, old-book, orbital, plan9, solarized, tufte, weyland-yutani, zenburn
 		reg.emplace_back(std::make_unique<detail::AmberTheme>());
 		reg.emplace_back(std::make_unique<detail::EInkTheme>());
 		reg.emplace_back(std::make_unique<detail::EverforestTheme>());
 		reg.emplace_back(std::make_unique<detail::GruvboxTheme>());
 		reg.emplace_back(std::make_unique<detail::KanagawaPaperTheme>());
 		reg.emplace_back(std::make_unique<detail::LCARSTheme>());
+		reg.emplace_back(std::make_unique<detail::LeuchtturmTheme>());
 		reg.emplace_back(std::make_unique<detail::NordTheme>());
 		reg.emplace_back(std::make_unique<detail::OldBookTheme>());
 		reg.emplace_back(std::make_unique<detail::OrbitalTheme>());
 		reg.emplace_back(std::make_unique<detail::Plan9Theme>());
 		reg.emplace_back(std::make_unique<detail::SolarizedTheme>());
+		reg.emplace_back(std::make_unique<detail::TufteTheme>());
 		reg.emplace_back(std::make_unique<detail::WeylandYutaniTheme>());
 		reg.emplace_back(std::make_unique<detail::ZenburnTheme>());
 	}
@@ -845,20 +895,24 @@ ThemeIndexFromId(const ThemeId id)
 		return 4;
 	case ThemeId::LCARS:
 		return 5;
-	case ThemeId::Nord:
+	case ThemeId::Leuchtturm:
 		return 6;
-	case ThemeId::OldBook:
+	case ThemeId::Nord:
 		return 7;
-	case ThemeId::Orbital:
+	case ThemeId::OldBook:
 		return 8;
-	case ThemeId::Plan9:
+	case ThemeId::Orbital:
 		return 9;
-	case ThemeId::Solarized:
+	case ThemeId::Plan9:
 		return 10;
-	case ThemeId::WeylandYutani:
+	case ThemeId::Solarized:
 		return 11;
-	case ThemeId::Zenburn:
+	case ThemeId::Tufte:
 		return 12;
+	case ThemeId::WeylandYutani:
+		return 13;
+	case ThemeId::Zenburn:
+		return 14;
 	}
 	return 0;
 }
@@ -882,30 +936,144 @@ ThemeIdFromIndex(const size_t idx)
 	case 5:
 		return ThemeId::LCARS;
 	case 6:
-		return ThemeId::Nord;
+		return ThemeId::Leuchtturm;
 	case 7:
-		return ThemeId::OldBook;
+		return ThemeId::Nord;
 	case 8:
-		return ThemeId::Orbital;
+		return ThemeId::OldBook;
 	case 9:
-		return ThemeId::Plan9;
+		return ThemeId::Orbital;
 	case 10:
-		return ThemeId::Solarized;
+		return ThemeId::Plan9;
 	case 11:
-		return ThemeId::WeylandYutani;
+		return ThemeId::Solarized;
 	case 12:
+		return ThemeId::Tufte;
+	case 13:
+		return ThemeId::WeylandYutani;
+	case 14:
 		return ThemeId::Zenburn;
 	}
 }
 
 
 // --- Syntax palette (v1): map TokenKind to ink color per current theme/background ---
+
+// Tufte palette: high-contrast, restrained color. Body text is true black on
+// cream; only keywords and links get subtle color to avoid a "christmas tree."
+static ImVec4
+SyntaxInkTufte(const TokenKind k, const bool dark)
+{
+	const ImVec4 ink  = dark ? RGBA(0xEAE6DE) : RGBA(0x111111); // body text
+	const ImVec4 dim  = dark ? RGBA(0x8A8680) : RGBA(0x555555); // comments
+	const ImVec4 red  = dark ? RGBA(0xD06060) : RGBA(0x8B0000); // keywords/preproc
+	const ImVec4 navy = dark ? RGBA(0x7098C0) : RGBA(0x1A3A5C); // functions/links
+	const ImVec4 grn  = dark ? RGBA(0x8AAA6E) : RGBA(0x2E5E2E); // strings
+	switch (k) {
+	case TokenKind::Keyword:
+	case TokenKind::Preproc:
+		return red;
+	case TokenKind::String:
+	case TokenKind::Char:
+		return grn;
+	case TokenKind::Comment:
+		return dim;
+	case TokenKind::Function:
+		return navy;
+	case TokenKind::Number:
+	case TokenKind::Constant:
+		return dark ? RGBA(0xC8A85A) : RGBA(0x6B4C00);
+	case TokenKind::Type:
+		return dark ? RGBA(0xBBAA90) : RGBA(0x333333);
+	case TokenKind::Error:
+		return dark ? RGBA(0xD06060) : RGBA(0xCC0000);
+	default:
+		return ink;
+	}
+}
+
+
+// Leuchtturm palette: blue-black fountain pen ink with brass and bronze accents.
+// Body text is ink-colored; accents drawn from the pen metals.
+static ImVec4
+SyntaxInkLeuchtturm(const TokenKind k, const bool dark)
+{
+	const ImVec4 ink   = dark ? RGBA(0xE5DDD0) : RGBA(0x040720); // fountain pen ink
+	const ImVec4 dim   = dark ? RGBA(0x7A7060) : RGBA(0x6A6558); // comments
+	const ImVec4 brass = dark ? RGBA(0xB8A060) : RGBA(0x504518); // patinated brass
+	const ImVec4 bronze= dark ? RGBA(0xC08050) : RGBA(0x5C3010); // dark bronze
+	const ImVec4 navy  = dark ? RGBA(0x8898B0) : RGBA(0x1C2E4A); // deep navy
+	switch (k) {
+	case TokenKind::Keyword:
+	case TokenKind::Preproc:
+		return brass;
+	case TokenKind::String:
+	case TokenKind::Char:
+		return bronze;
+	case TokenKind::Comment:
+		return dim;
+	case TokenKind::Function:
+		return navy;
+	case TokenKind::Number:
+	case TokenKind::Constant:
+		return dark ? RGBA(0xA89060) : RGBA(0x483C10);
+	case TokenKind::Type:
+		return dark ? RGBA(0xC0B898) : RGBA(0x222238);
+	case TokenKind::Error:
+		return dark ? RGBA(0xD06060) : RGBA(0xA02020);
+	default:
+		return ink;
+	}
+}
+
+
+// Everforest: warm forest palette on dark green-gray (bg 0x2B3339).
+// Default comment color (0x616E88) is too dim; boost it and tune others.
+static ImVec4
+SyntaxInkEverforest(const TokenKind k)
+{
+	switch (k) {
+	case TokenKind::Keyword:
+		return RGBA(0xE67E80); // everforest red
+	case TokenKind::Type:
+		return RGBA(0xD699B6); // everforest purple
+	case TokenKind::String:
+	case TokenKind::Char:
+		return RGBA(0xA7C080); // everforest green
+	case TokenKind::Comment:
+		return RGBA(0x859289); // boosted from 0x616E88 for contrast
+	case TokenKind::Number:
+	case TokenKind::Constant:
+		return RGBA(0xD8A657); // everforest yellow/orange
+	case TokenKind::Preproc:
+		return RGBA(0xE69875); // everforest orange
+	case TokenKind::Function:
+		return RGBA(0x83C092); // everforest aqua
+	case TokenKind::Operator:
+	case TokenKind::Punctuation:
+		return RGBA(0xD3C6AA); // everforest fg
+	case TokenKind::Error:
+		return RGBA(0xE67E80);
+	default:
+		return RGBA(0xD3C6AA); // everforest fg
+	}
+}
+
+
 [[maybe_unused]] static ImVec4
 SyntaxInk(const TokenKind k)
 {
-	// Basic palettes for dark/light backgrounds; tuned for Nord-ish defaults
 	const bool dark = (GetBackgroundMode() == BackgroundMode::Dark);
-	// Base text
+
+	// Per-theme syntax palettes
+	if (gCurrentTheme == ThemeId::Tufte)
+		return SyntaxInkTufte(k, dark);
+	if (gCurrentTheme == ThemeId::Leuchtturm)
+		return SyntaxInkLeuchtturm(k, dark);
+	if (gCurrentTheme == ThemeId::Everforest)
+		return SyntaxInkEverforest(k);
+
+	// Default palettes tuned for Nord-ish themes
 	const ImVec4 def = dark ? RGBA(0xD8DEE9) : RGBA(0x2E3440);
 	switch (k) {
 	case TokenKind::Keyword:

HelpText.cc

@@ -27,6 +27,7 @@ HelpText::Text()
 		"  C-k SPACE    Toggle mark\n"
 		"  C-k C-d      Kill entire line\n"
 		"  C-k C-q      Quit now (no confirm)\n"
+		"  C-k C-s      Save\n"
 		"  C-k C-x      Save and quit\n"
 		"  C-k a        Mark start of file, jump to end\n"
 		"  C-k b        Switch buffer\n"
@@ -40,6 +41,7 @@ HelpText::Text()
 		"  C-k j        Jump to mark\n"
 		"  C-k k        Center viewport on cursor\n"
 		"  C-k l        Reload buffer from disk\n"
+		"  C-k m        Toggle edit mode (code/writing)\n"
 		"  C-k n        Previous buffer\n"
 		"  C-k o        Change working directory (prompt)\n"
 		"  C-k p        Next buffer\n"
@@ -63,6 +65,10 @@ HelpText::Text()
 		"  ESC BACKSPACE Delete previous word (Alt-Backspace)\n"
 		"  ESC q        Reflow paragraph\n"
 		"\n"
+		"Universal argument:\n"
+		"  C-u           Begin repeat count (then type digits); C-u alone multiplies by 4\n"
+		"  C-u N <cmd>   Repeat <cmd> N times (e.g., C-u 8 C-f moves right 8 chars)\n"
+		"\n"
 		"Control keys:\n"
 		"  C-a C-e      Line start / end\n"
 		"  C-b C-f      Move left / right\n"
@@ -74,12 +80,32 @@ HelpText::Text()
 		"  C-t          Regex search & replace\n"
 		"  C-h          Search & replace\n"
 		"  C-l / C-g    Refresh / Cancel\n"
-		"  C-u [digits] Universal argument (repeat count)\n"
 		"\n"
 		"Buffers:\n  +HELP+ is read-only. Press C-k ' to toggle; C-k h restores it.\n"
 		"\n"
-		"GUI appearance (command prompt):\n"
+		"Edit modes:\n"
-		"  : theme NAME         Set GUI theme (amber, eink, everforest, gruvbox, kanagawa-paper, lcars, nord, old-book, plan9, solarized, weyland-yutani, zenburn)\n"
+		"  code         Monospace font (default for source files)\n"
-		"  : background MODE    Set background: light | dark (affects eink, gruvbox, old-book, solarized)\n"
+		"  writing      Proportional font (auto for .txt, .md, .rst, .org, .tex)\n"
+		"  C-k m or : mode [code|writing] to toggle\n"
+		"\n"
+		"GUI commands (command prompt):\n"
+		"  : theme NAME         Set theme (amber, eink, everforest, gruvbox,\n"
+		"                       kanagawa-paper, lcars, leuchtturm, nord, old-book,\n"
+		"                       orbital, plan9, solarized, tufte, weyland-yutani,\n"
+		"                       zenburn)\n"
+		"  : background MODE    Background: light | dark\n"
+		"  : font NAME          Set font (tab completes)\n"
+		"  : font-size NUM      Set font size in pixels\n"
+		"  : mode [code|writing] Toggle or set edit mode\n"
+		"\n"
+		"Configuration:\n"
+		"  Config file: ~/.config/kte/kge.toml (see CONFIG.md)\n"
+		"  Legacy kge.ini is also supported.\n"
+		"\n"
+		"GUI window management:\n"
+		"  Cmd+N (macOS)        Open a new editor window sharing the same buffers\n"
+		"  Ctrl+Shift+N (Linux) Open a new editor window sharing the same buffers\n"
+		"  Close window         Secondary windows close independently; closing the\n"
+		"                       primary window quits the editor\n"
 	);
 }

ImGuiFrontend.cc

@@ -29,21 +29,152 @@
 
 static auto kGlslVersion = "#version 150"; // GL 3.2 core (macOS compatible)
 
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+static void
+apply_syntax_to_buffer(Buffer *b, const GUIConfig &cfg)
+{
+	if (!b)
+		return;
+
+	// Auto-detect edit mode from file extension once per buffer so that
+	// manual toggles (C-k m / : mode) are not overridden every frame.
+	if (!b->EditModeDetected() && !b->Filename().empty())
+		b->SetEditMode(DetectEditMode(b->Filename()));
+
+	// Writing mode disables syntax; otherwise follow the global config.
+	if (cfg.syntax && b->GetEditMode() != EditMode::Writing) {
+		b->SetSyntaxEnabled(true);
+		b->EnsureHighlighter();
+		if (auto *eng = b->Highlighter()) {
+			if (!eng->HasHighlighter()) {
+				std::string first_line;
+				const auto &rows = b->Rows();
+				if (!rows.empty())
+					first_line = static_cast<std::string>(rows[0]);
+				std::string ft = kte::HighlighterRegistry::DetectForPath(
+					b->Filename(), first_line);
+				if (!ft.empty()) {
+					eng->SetHighlighter(kte::HighlighterRegistry::CreateFor(ft));
+					b->SetFiletype(ft);
+					eng->InvalidateFrom(0);
+				} else {
+					eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
+					b->SetFiletype("");
+					eng->InvalidateFrom(0);
+				}
+			}
+		}
+	} else {
+		b->SetSyntaxEnabled(false);
+	}
+}
+
+
+// Update editor logical rows/cols from current ImGui metrics for a given display size.
+static void
+update_editor_dimensions(Editor &ed, float disp_w, float disp_h)
+{
+	float row_h = ImGui::GetTextLineHeightWithSpacing();
+	// Use average character width rather than "M" (the widest character)
+	// so that column count is reasonable for proportional fonts too.
+	float ch_w  = ImGui::CalcTextSize("abcdefghijklmnopqrstuvwxyz").x / 26.0f;
+	if (row_h <= 0.0f)
+		row_h = 16.0f;
+	if (ch_w <= 0.0f)
+		ch_w = 8.0f;
+
+	const float pad_x = 6.0f;
+	const float pad_y = 6.0f;
+
+	float wanted_bar_h   = ImGui::GetFrameHeight();
+	float total_avail_h  = std::max(0.0f, disp_h - 2.0f * pad_y);
+	float actual_avail_h = std::floor((total_avail_h - wanted_bar_h) / row_h) * row_h;
+
+	auto content_rows = static_cast<std::size_t>(std::max(0.0f, std::floor(actual_avail_h / row_h)));
+	std::size_t rows  = content_rows + 1;
+
+	float avail_w    = std::max(0.0f, disp_w - 2.0f * pad_x);
+	std::size_t cols = static_cast<std::size_t>(std::max(1.0f, std::floor(avail_w / ch_w)));
+
+	if (rows != ed.Rows() || cols != ed.Cols()) {
+		ed.SetDimensions(rows, cols);
+	}
+}
+
+
+// ---------------------------------------------------------------------------
+// SetupImGuiStyle_ — apply theme, fonts, and flags to the current ImGui context
+// ---------------------------------------------------------------------------
+void
+GUIFrontend::SetupImGuiStyle_()
+{
+	ImGuiIO &io = ImGui::GetIO();
+
+	// Disable imgui.ini for secondary windows (primary sets its own path in Init)
+	io.IniFilename = nullptr;
+
+	io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
+	io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
+	ImGui::StyleColorsDark();
+
+	if (config_.background == "light")
+		kte::SetBackgroundMode(kte::BackgroundMode::Light);
+	else
+		kte::SetBackgroundMode(kte::BackgroundMode::Dark);
+	kte::ApplyThemeByName(config_.theme);
+
+	// Load fonts into this context's font atlas.
+	// Font registry is global and already populated by Init; just load into this atlas.
+	if (!kte::Fonts::FontRegistry::Instance().LoadFont(config_.font, (float) config_.font_size)) {
+		LoadGuiFont_(nullptr, (float) config_.font_size);
+	}
+}
+
+
+// ---------------------------------------------------------------------------
+// Destroy a single window's ImGui context + SDL/GL resources
+// ---------------------------------------------------------------------------
+void
+GUIFrontend::DestroyWindowResources_(WindowState &ws)
+{
+	if (ws.imgui_ctx) {
+		// Must activate this window's GL context before shutting down the
+		// OpenGL3 backend, otherwise it deletes another context's resources.
+		if (ws.window && ws.gl_ctx)
+			SDL_GL_MakeCurrent(ws.window, ws.gl_ctx);
+		ImGui::SetCurrentContext(ws.imgui_ctx);
+		ImGui_ImplOpenGL3_Shutdown();
+		ImGui_ImplSDL2_Shutdown();
+		ImGui::DestroyContext(ws.imgui_ctx);
+		ws.imgui_ctx = nullptr;
+	}
+	if (ws.gl_ctx) {
+		SDL_GL_DeleteContext(ws.gl_ctx);
+		ws.gl_ctx = nullptr;
+	}
+	if (ws.window) {
+		SDL_DestroyWindow(ws.window);
+		ws.window = nullptr;
+	}
+}
+
+
 bool
 GUIFrontend::Init(int &argc, char **argv, Editor &ed)
 {
 	(void) argc;
 	(void) argv;
-	// Attach editor to input handler for editor-owned features (e.g., universal argument)
+
-	input_.Attach(&ed);
+	// Load GUI configuration (fullscreen, columns/rows, font size, theme, background)
-	// editor dimensions will be initialized during the first Step() frame
+	config_ = GUIConfig::Load();
+
 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) != 0) {
 		return false;
 	}
 
-	// Load GUI configuration (fullscreen, columns/rows, font size, theme, background)
-	GUIConfig cfg = GUIConfig::Load();
-
 	// GL attributes for core profile
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
@@ -56,159 +187,114 @@ GUIFrontend::Init(int &argc, char **argv, Editor &ed)
 	// Compute desired window size from config
 	Uint32 win_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI;
 
-	if (cfg.fullscreen) {
+	int init_w = 1280, init_h = 800;
-		// "Fullscreen": fill the usable bounds of the primary display.
+	if (config_.fullscreen) {
-		// On macOS, do NOT use true fullscreen so the menu/status bar remains visible.
 		SDL_Rect usable{};
 		if (SDL_GetDisplayUsableBounds(0, &usable) == 0) {
-			width_  = usable.w;
+			init_w = usable.w;
-			height_ = usable.h;
+			init_h = usable.h;
 		}
 #if !defined(__APPLE__)
-		// Non-macOS: desktop fullscreen uses the current display resolution.
 		win_flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
 #endif
 	} else {
-		// Windowed: width = columns * font_size, height = (rows * 2) * font_size
+		int w = config_.columns * static_cast<int>(config_.font_size);
-		int w = cfg.columns * static_cast<int>(cfg.font_size);
+		int h = config_.rows * static_cast<int>(config_.font_size * 1.2);
-		int h = cfg.rows * static_cast<int>(cfg.font_size * 1.2);
-
-		// As a safety, clamp to display usable bounds if retrievable
 		SDL_Rect usable{};
 		if (SDL_GetDisplayUsableBounds(0, &usable) == 0) {
 			w = std::min(w, usable.w);
 			h = std::min(h, usable.h);
 		}
-		width_  = std::max(320, w);
+		init_w = std::max(320, w);
-		height_ = std::max(200, h);
+		init_h = std::max(200, h);
 	}
 
 	SDL_SetHint(SDL_HINT_VIDEO_ALLOW_SCREENSAVER, "1");
-	window_ = SDL_CreateWindow(
+	SDL_Window *win = SDL_CreateWindow(
 		"kge - kyle's graphical editor " KTE_VERSION_STR,
 		SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
-		width_, height_,
+		init_w, init_h,
 		win_flags);
-	if (!window_) {
+	if (!win) {
 		return false;
 	}
 
 	SDL_EnableScreenSaver();
 
 #if defined(__APPLE__)
-	// macOS: when "fullscreen" is requested, position the window at the
+	if (config_.fullscreen) {
-	// top-left of the usable display area to mimic fullscreen while keeping
-	// the system menu bar visible.
-	if (cfg.fullscreen) {
 		SDL_Rect usable{};
 		if (SDL_GetDisplayUsableBounds(0, &usable) == 0) {
-			SDL_SetWindowPosition(window_, usable.x, usable.y);
+			SDL_SetWindowPosition(win, usable.x, usable.y);
 		}
 	}
 #endif
 
-	gl_ctx_ = SDL_GL_CreateContext(window_);
+	SDL_GLContext gl_ctx = SDL_GL_CreateContext(win);
-	if (!gl_ctx_)
+	if (!gl_ctx) {
+		SDL_DestroyWindow(win);
 		return false;
-	SDL_GL_MakeCurrent(window_, gl_ctx_);
+	}
+	SDL_GL_MakeCurrent(win, gl_ctx);
 	SDL_GL_SetSwapInterval(1); // vsync
 
+	// Create primary ImGui context
 	IMGUI_CHECKVERSION();
-	ImGui::CreateContext();
+	ImGuiContext *imgui_ctx = ImGui::CreateContext();
 	ImGuiIO &io             = ImGui::GetIO();
 
 	// Set custom ini filename path to ~/.config/kte/imgui.ini
 	if (const char *home = std::getenv("HOME")) {
 		namespace fs = std::filesystem;
 		fs::path config_dir = fs::path(home) / ".config" / "kte";
-
 		std::error_code ec;
 		if (!fs::exists(config_dir)) {
 			fs::create_directories(config_dir, ec);
 		}
-
 		if (fs::exists(config_dir)) {
 			static std::string ini_path = (config_dir / "imgui.ini").string();
 			io.IniFilename              = ini_path.c_str();
 		}
 	}
 
-	io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
+	io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
-	io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
+	io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
 	ImGui::StyleColorsDark();
 
-	// Apply background mode and selected theme (default: Nord). Can be changed at runtime via commands.
+	if (config_.background == "light")
-	if (cfg.background == "light")
 		kte::SetBackgroundMode(kte::BackgroundMode::Light);
 	else
 		kte::SetBackgroundMode(kte::BackgroundMode::Dark);
-	kte::ApplyThemeByName(cfg.theme);
+	kte::ApplyThemeByName(config_.theme);
 
-	// Apply default syntax highlighting preference from GUI config to the current buffer
+	apply_syntax_to_buffer(ed.CurrentBuffer(), config_);
-	if (Buffer *b = ed.CurrentBuffer()) {
-		if (cfg.syntax) {
-			b->SetSyntaxEnabled(true);
-			// Ensure a highlighter is available if possible
-			b->EnsureHighlighter();
-			if (auto *eng = b->Highlighter()) {
-				if (!eng->HasHighlighter()) {
-					// Try detect from filename and first line; fall back to cpp or existing filetype
-					std::string first_line;
-					const auto &rows = b->Rows();
-					if (!rows.empty())
-						first_line = static_cast<std::string>(rows[0]);
-					std::string ft = kte::HighlighterRegistry::DetectForPath(
-						b->Filename(), first_line);
-					if (!ft.empty()) {
-						eng->SetHighlighter(kte::HighlighterRegistry::CreateFor(ft));
-						b->SetFiletype(ft);
-						eng->InvalidateFrom(0);
-					} else {
-						// Unknown/unsupported -> install a null highlighter to keep syntax enabled
-						eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
-						b->SetFiletype("");
-						eng->InvalidateFrom(0);
-					}
-				}
-			}
-		} else {
-			b->SetSyntaxEnabled(false);
-		}
-	}
 
-	if (!ImGui_ImplSDL2_InitForOpenGL(window_, gl_ctx_))
+	if (!ImGui_ImplSDL2_InitForOpenGL(win, gl_ctx))
 		return false;
 	if (!ImGui_ImplOpenGL3_Init(kGlslVersion))
 		return false;
 
-	// Cache initial window size; logical rows/cols will be computed in Step() once a valid ImGui frame exists
+	// Cache initial window size
 	int w, h;
-	SDL_GetWindowSize(window_, &w, &h);
+	SDL_GetWindowSize(win, &w, &h);
-	width_  = w;
+	init_w = w;
-	height_ = h;
+	init_h = h;
 
 #if defined(__APPLE__)
-	// Workaround: On macOS Retina when starting maximized, we sometimes get a
-	// subtle input vs draw alignment mismatch until the first manual resize.
-	// Nudge the window size by 1px and back to trigger a proper internal
-	// recomputation, without visible impact.
 	if (w > 1 && h > 1) {
-		SDL_SetWindowSize(window_, w - 1, h - 1);
+		SDL_SetWindowSize(win, w - 1, h - 1);
-		SDL_SetWindowSize(window_, w, h);
+		SDL_SetWindowSize(win, w, h);
-		// Update cached size in case backend reports immediately
+		SDL_GetWindowSize(win, &w, &h);
-		SDL_GetWindowSize(window_, &w, &h);
+		init_w = w;
-		width_  = w;
+		init_h = h;
-		height_ = h;
 	}
 #endif
 
-	// Install embedded fonts into registry and load configured font
+	// Install embedded fonts
 	kte::Fonts::InstallDefaultFonts();
-	// Initialize font atlas using configured font name and size; fallback to embedded default helper
+	if (!kte::Fonts::FontRegistry::Instance().LoadFont(config_.font, (float) config_.font_size)) {
-	if (!kte::Fonts::FontRegistry::Instance().LoadFont(cfg.font, (float) cfg.font_size)) {
+		LoadGuiFont_(nullptr, (float) config_.font_size);
-		LoadGuiFont_(nullptr, (float) cfg.font_size);
+		kte::Fonts::FontRegistry::Instance().RequestLoadFont("default", (float) config_.font_size);
-		// Record defaults in registry so subsequent size changes have a base
-		kte::Fonts::FontRegistry::Instance().RequestLoadFont("default", (float) cfg.font_size);
 		std::string n;
 		float s = 0.0f;
 		if (kte::Fonts::FontRegistry::Instance().ConsumePendingFontRequest(n, s)) {
@@ -216,6 +302,90 @@ GUIFrontend::Init(int &argc, char **argv, Editor &ed)
 		}
 	}
 
+	// Build primary WindowState
+	auto ws       = std::make_unique<WindowState>();
+	ws->window    = win;
+	ws->gl_ctx    = gl_ctx;
+	ws->imgui_ctx = imgui_ctx;
+	ws->width     = init_w;
+	ws->height    = init_h;
+	// The primary window's editor IS the editor passed in from main; we don't
+	// use ws->editor for the primary — instead we keep a pointer to &ed.
+	// We store a sentinel: window index 0 uses the external editor reference.
+	// To keep things simple, attach input to the passed-in editor.
+	ws->input.Attach(&ed);
+	windows_.push_back(std::move(ws));
+
+	return true;
+}
+
+
+bool
+GUIFrontend::OpenNewWindow_(Editor &primary)
+{
+	Uint32 win_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI;
+	int w            = windows_[0]->width;
+	int h            = windows_[0]->height;
+
+	SDL_Window *win = SDL_CreateWindow(
+		"kge - kyle's graphical editor " KTE_VERSION_STR,
+		SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+		w, h,
+		win_flags);
+	if (!win)
+		return false;
+
+	SDL_GLContext gl_ctx = SDL_GL_CreateContext(win);
+	if (!gl_ctx) {
+		SDL_DestroyWindow(win);
+		return false;
+	}
+	SDL_GL_MakeCurrent(win, gl_ctx);
+	SDL_GL_SetSwapInterval(1);
+
+	// Each window gets its own ImGui context — ImGui requires exactly one
+	// NewFrame/Render cycle per context per frame.
+	ImGuiContext *imgui_ctx = ImGui::CreateContext();
+	ImGui::SetCurrentContext(imgui_ctx);
+
+	SetupImGuiStyle_();
+
+	if (!ImGui_ImplSDL2_InitForOpenGL(win, gl_ctx)) {
+		ImGui::DestroyContext(imgui_ctx);
+		SDL_GL_DeleteContext(gl_ctx);
+		SDL_DestroyWindow(win);
+		return false;
+	}
+	if (!ImGui_ImplOpenGL3_Init(kGlslVersion)) {
+		ImGui_ImplSDL2_Shutdown();
+		ImGui::DestroyContext(imgui_ctx);
+		SDL_GL_DeleteContext(gl_ctx);
+		SDL_DestroyWindow(win);
+		return false;
+	}
+
+	auto ws       = std::make_unique<WindowState>();
+	ws->window    = win;
+	ws->gl_ctx    = gl_ctx;
+	ws->imgui_ctx = imgui_ctx;
+	ws->width     = w;
+	ws->height    = h;
+
+	// Secondary editor shares the primary's buffer list
+	ws->editor.SetSharedBuffers(&primary.Buffers());
+	ws->editor.SetDimensions(primary.Rows(), primary.Cols());
+
+	// Open a new untitled buffer and switch to it in the new window.
+	ws->editor.AddBuffer(Buffer());
+	ws->editor.SwitchTo(ws->editor.BufferCount() - 1);
+
+	ws->input.Attach(&ws->editor);
+
+	windows_.push_back(std::move(ws));
+
+	// Restore primary context
+	ImGui::SetCurrentContext(windows_[0]->imgui_ctx);
+	SDL_GL_MakeCurrent(windows_[0]->window, windows_[0]->gl_ctx);
 	return true;
 }
 
@@ -223,137 +393,249 @@ GUIFrontend::Init(int &argc, char **argv, Editor &ed)
 void
 GUIFrontend::Step(Editor &ed, bool &running)
 {
+	// --- Event processing ---
+	// SDL events carry a window ID. Route each event to the correct window's
+	// ImGui context (for ImGui_ImplSDL2_ProcessEvent) and input handler.
 	SDL_Event e;
 	while (SDL_PollEvent(&e)) {
-		ImGui_ImplSDL2_ProcessEvent(&e);
+		// Determine which window this event belongs to
+		Uint32 event_win_id = 0;
 		switch (e.type) {
-		case SDL_QUIT:
-			running = false;
-			break;
 		case SDL_WINDOWEVENT:
-			if (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
+			event_win_id = e.window.windowID;
-				width_  = e.window.data1;
+			break;
-				height_ = e.window.data2;
+		case SDL_KEYDOWN:
-			}
+		case SDL_KEYUP:
+			event_win_id = e.key.windowID;
+			break;
+		case SDL_TEXTINPUT:
+			event_win_id = e.text.windowID;
+			break;
+		case SDL_MOUSEBUTTONDOWN:
+		case SDL_MOUSEBUTTONUP:
+			event_win_id = e.button.windowID;
+			break;
+		case SDL_MOUSEWHEEL:
+			event_win_id = e.wheel.windowID;
+			break;
+		case SDL_MOUSEMOTION:
+			event_win_id = e.motion.windowID;
 			break;
 		default:
 			break;
 		}
-		// Map input to commands
+
-		input_.ProcessSDLEvent(e);
+		if (e.type == SDL_QUIT) {
+			running = false;
+			break;
 		}
 
-	// Apply pending font change before starting a new frame
+		// Find the target window and route the event to its ImGui context
+		WindowState *target = nullptr;
+		std::size_t target_idx = 0;
+		if (event_win_id != 0) {
+			for (std::size_t i = 0; i < windows_.size(); ++i) {
+				if (SDL_GetWindowID(windows_[i]->window) == event_win_id) {
+					target     = windows_[i].get();
+					target_idx = i;
+					break;
+				}
+			}
+		}
+
+		if (target && target->imgui_ctx) {
+			// Set this window's ImGui context so ImGui_ImplSDL2_ProcessEvent
+			// updates the correct IO state.
+			ImGui::SetCurrentContext(target->imgui_ctx);
+			ImGui_ImplSDL2_ProcessEvent(&e);
+		}
+
+		if (e.type == SDL_WINDOWEVENT) {
+			if (e.window.event == SDL_WINDOWEVENT_CLOSE) {
+				if (target) {
+					if (target_idx == 0) {
+						running = false;
+					} else {
+						target->alive = false;
+					}
+				}
+			} else if (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
+				if (target) {
+					target->width  = e.window.data1;
+					target->height = e.window.data2;
+				}
+			}
+		}
+
+		// Route input events to the correct window's input handler
+		if (target) {
+			target->input.ProcessSDLEvent(e);
+		}
+	}
+
+	if (!running)
+		return;
+
+	// --- Apply pending font change (to all contexts) ---
 	{
 		std::string fname;
 		float fsize = 0.0f;
 		if (kte::Fonts::FontRegistry::Instance().ConsumePendingFontRequest(fname, fsize)) {
 			if (!fname.empty() && fsize > 0.0f) {
+				for (auto &ws : windows_) {
+					if (!ws->alive || !ws->imgui_ctx)
+						continue;
+					ImGui::SetCurrentContext(ws->imgui_ctx);
+					SDL_GL_MakeCurrent(ws->window, ws->gl_ctx);
 					kte::Fonts::FontRegistry::Instance().LoadFont(fname, fsize);
-				// Recreate backend font texture
 					ImGui_ImplOpenGL3_DestroyFontsTexture();
 					ImGui_ImplOpenGL3_CreateFontsTexture();
 				}
 			}
 		}
+	}
 
-	// Start a new ImGui frame BEFORE processing commands so dimensions are correct
+	// --- Step each window ---
+	// We iterate by index because OpenNewWindow_ may append to windows_.
+	for (std::size_t wi = 0; wi < windows_.size(); ++wi) {
+		WindowState &ws = *windows_[wi];
+		if (!ws.alive)
+			continue;
+
+		Editor &wed = (wi == 0) ? ed : ws.editor;
+
+		// Shared buffer list may have been modified by another window.
+		wed.ValidateBufferIndex();
+
+		// Activate this window's GL and ImGui contexts
+		SDL_GL_MakeCurrent(ws.window, ws.gl_ctx);
+		ImGui::SetCurrentContext(ws.imgui_ctx);
+
+		// Start a new ImGui frame
 		ImGui_ImplOpenGL3_NewFrame();
-	ImGui_ImplSDL2_NewFrame(window_);
+		ImGui_ImplSDL2_NewFrame(ws.window);
 		ImGui::NewFrame();
 
-	// Update editor logical rows/cols using current ImGui metrics and display size
+		// Update editor dimensions
 		{
 			ImGuiIO &io  = ImGui::GetIO();
-		float row_h = ImGui::GetTextLineHeightWithSpacing();
+			float disp_w = io.DisplaySize.x > 0 ? io.DisplaySize.x : static_cast<float>(ws.width);
-		float ch_w  = ImGui::CalcTextSize("M").x;
+			float disp_h = io.DisplaySize.y > 0 ? io.DisplaySize.y : static_cast<float>(ws.height);
-		if (row_h <= 0.0f)
+			update_editor_dimensions(wed, disp_w, disp_h);
-			row_h = 16.0f;
-		if (ch_w <= 0.0f)
-			ch_w = 8.0f;
-		// Prefer ImGui IO display size; fall back to cached SDL window size
-		float disp_w = io.DisplaySize.x > 0 ? io.DisplaySize.x : static_cast<float>(width_);
-		float disp_h = io.DisplaySize.y > 0 ? io.DisplaySize.y : static_cast<float>(height_);
-
-		// Account for the GUI window padding and the status bar height used in ImGuiRenderer.
-		const float pad_x = 6.0f;
-		const float pad_y = 6.0f;
-
-		// Use the same logic as ImGuiRenderer for available height and status bar reservation.
-		float wanted_bar_h   = ImGui::GetFrameHeight();
-		float total_avail_h  = std::max(0.0f, disp_h - 2.0f * pad_y);
-		float actual_avail_h = std::floor((total_avail_h - wanted_bar_h) / row_h) * row_h;
-
-		// Visible content rows inside the scroll child
-		auto content_rows = static_cast<std::size_t>(std::max(0.0f, std::floor(actual_avail_h / row_h)));
-		// Editor::Rows includes the status line; add 1 back for it.
-		std::size_t rows = content_rows + 1;
-
-		float avail_w    = std::max(0.0f, disp_w - 2.0f * pad_x);
-		std::size_t cols = static_cast<std::size_t>(std::max(1.0f, std::floor(avail_w / ch_w)));
-
-		// Only update if changed to avoid churn
-		if (rows != ed.Rows() || cols != ed.Cols()) {
-			ed.SetDimensions(rows, cols);
-		}
 		}
 
-	// Allow deferred opens (including swap recovery prompts) to run.
+		// Allow deferred opens
-	ed.ProcessPendingOpens();
+		wed.ProcessPendingOpens();
 
-	// Execute pending mapped inputs (drain queue) AFTER dimensions are updated
+		// Ensure newly opened buffers get syntax + edit mode detection
+		apply_syntax_to_buffer(wed.CurrentBuffer(), config_);
+
+		// Drain input queue
 		for (;;) {
 			MappedInput mi;
-		if (!input_.Poll(mi))
+			if (!ws.input.Poll(mi))
 				break;
 			if (mi.hasCommand) {
-			// Track kill ring before and after to sync GUI clipboard when it changes
+				if (mi.id == CommandId::NewWindow) {
-			const std::string before = ed.KillRingHead();
+					// Open a new window; handled after this loop
-			Execute(ed, mi.id, mi.arg, mi.count);
+					wed.SetNewWindowRequested(true);
-			const std::string after = ed.KillRingHead();
+				} else if (mi.id == CommandId::FontZoomIn ||
+				           mi.id == CommandId::FontZoomOut ||
+				           mi.id == CommandId::FontZoomReset) {
+					auto &fr = kte::Fonts::FontRegistry::Instance();
+					float cur = fr.CurrentFontSize();
+					if (cur <= 0.0f) cur = config_.font_size;
+					float next = cur;
+					if (mi.id == CommandId::FontZoomIn)
+						next = std::min(cur + 2.0f, 72.0f);
+					else if (mi.id == CommandId::FontZoomOut)
+						next = std::max(cur - 2.0f, 8.0f);
+					else
+						next = config_.font_size; // reset to config default
+					if (next != cur)
+						fr.RequestLoadFont(fr.CurrentFontName(), next);
+				} else {
+					const std::string before = wed.KillRingHead();
+					Execute(wed, mi.id, mi.arg, mi.count);
+					const std::string after = wed.KillRingHead();
 					if (after != before && !after.empty()) {
-				// Update the system clipboard to mirror the kill ring head in GUI
 						SDL_SetClipboardText(after.c_str());
 					}
 				}
 			}
+		}
 
-	if (ed.QuitRequested()) {
+		if (wi == 0 && wed.QuitRequested()) {
 			running = false;
 		}
 
-	// No runtime font UI; always use embedded font.
+		// Switch font based on current buffer's edit mode (deferred to next frame)
+		{
+			Buffer *cur = wed.CurrentBuffer();
+			if (cur) {
+				auto &fr = kte::Fonts::FontRegistry::Instance();
+				const std::string &expected =
+					(cur->GetEditMode() == EditMode::Writing)
+						? config_.writing_font
+						: config_.code_font;
+				if (fr.CurrentFontName() != expected && fr.HasFont(expected)) {
+					float sz = fr.CurrentFontSize();
+					if (sz <= 0.0f) sz = config_.font_size;
+					fr.RequestLoadFont(expected, sz);
+				}
+			}
+		}
 
-	// Draw editor UI
+		// Draw
-	renderer_.Draw(ed);
+		ws.renderer.Draw(wed);
 
 		// Render
 		ImGui::Render();
 		int display_w, display_h;
-	SDL_GL_GetDrawableSize(window_, &display_w, &display_h);
+		SDL_GL_GetDrawableSize(ws.window, &display_w, &display_h);
 		glViewport(0, 0, display_w, display_h);
 		glClearColor(0.1f, 0.1f, 0.11f, 1.0f);
 		glClear(GL_COLOR_BUFFER_BIT);
 		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
-	SDL_GL_SwapWindow(window_);
+		SDL_GL_SwapWindow(ws.window);
+	}
+
+	// Handle deferred new-window requests (must happen outside the render loop
+	// to avoid corrupting an in-progress ImGui frame).
+	for (std::size_t wi = 0; wi < windows_.size(); ++wi) {
+		Editor &wed = (wi == 0) ? ed : windows_[wi]->editor;
+		if (wed.NewWindowRequested()) {
+			wed.SetNewWindowRequested(false);
+			OpenNewWindow_(ed);
+		}
+	}
+
+	// Remove dead secondary windows
+	for (auto it = windows_.begin() + 1; it != windows_.end();) {
+		if (!(*it)->alive) {
+			DestroyWindowResources_(**it);
+			it = windows_.erase(it);
+		} else {
+			++it;
+		}
+	}
+
+	// Restore primary context
+	if (!windows_.empty()) {
+		ImGui::SetCurrentContext(windows_[0]->imgui_ctx);
+		SDL_GL_MakeCurrent(windows_[0]->window, windows_[0]->gl_ctx);
+	}
 }
 
 
 void
 GUIFrontend::Shutdown()
 {
-	ImGui_ImplOpenGL3_Shutdown();
+	// Destroy all windows (secondary first, then primary)
-	ImGui_ImplSDL2_Shutdown();
+	for (auto it = windows_.rbegin(); it != windows_.rend(); ++it) {
-	ImGui::DestroyContext();
+		DestroyWindowResources_(**it);
-
-	if (gl_ctx_) {
-		SDL_GL_DeleteContext(gl_ctx_);
-		gl_ctx_ = nullptr;
-	}
-	if (window_) {
-		SDL_DestroyWindow(window_);
-		window_ = nullptr;
 	}
+	windows_.clear();
 	SDL_Quit();
 }
 
@@ -367,7 +649,6 @@ GUIFrontend::LoadGuiFont_(const char * /*path*/, const float size_px)
 	ImFontConfig config;
 	config.MergeMode = false;
 
-	// Load Basic Latin + Latin Supplement
 	io.Fonts->AddFontFromMemoryCompressedTTF(
 		kte::Fonts::DefaultFontData,
 		kte::Fonts::DefaultFontSize,
@@ -375,7 +656,6 @@ GUIFrontend::LoadGuiFont_(const char * /*path*/, const float size_px)
 		&config,
 		io.Fonts->GetGlyphRangesDefault());
 
-	// Merge Greek and Mathematical symbols from IosevkaExtended
 	config.MergeMode                       = true;
 	static const ImWchar extended_ranges[] = {
 		0x0370, 0x03FF, // Greek and Coptic

ImGuiFrontend.h

@@ -2,13 +2,18 @@
  * GUIFrontend - couples ImGuiInputHandler + GUIRenderer and owns SDL2/ImGui lifecycle
  */
 #pragma once
+#include <memory>
+#include <vector>
+
 #include "Frontend.h"
 #include "GUIConfig.h"
 #include "ImGuiInputHandler.h"
 #include "ImGuiRenderer.h"
+#include "Editor.h"
 
 
 struct SDL_Window;
+struct ImGuiContext;
 typedef void *SDL_GLContext;
 
 class GUIFrontend final : public Frontend {
@@ -24,13 +29,31 @@ public:
 	void Shutdown() override;
 
 private:
+	// Per-window state — each window owns its own ImGui context so that
+	// NewFrame/Render cycles are fully independent (ImGui requires exactly
+	// one NewFrame per Render per context).
+	struct WindowState {
+		SDL_Window *window       = nullptr;
+		SDL_GLContext gl_ctx     = nullptr;
+		ImGuiContext *imgui_ctx  = nullptr;
+		ImGuiInputHandler input{};
+		ImGuiRenderer renderer{};
+		Editor editor{};
+		int width  = 1280;
+		int height = 800;
+		bool alive = true;
+	};
+
+	// Open a new secondary window sharing the primary editor's buffer list.
+	// Returns false if window creation fails.
+	bool OpenNewWindow_(Editor &primary);
+
+	// Initialize fonts and theme for a given ImGui context (must be current).
+	void SetupImGuiStyle_();
+	static void DestroyWindowResources_(WindowState &ws);
 	static bool LoadGuiFont_(const char *path, float size_px);
 
 	GUIConfig config_{};
-	ImGuiInputHandler input_{};
+	// Primary window (index 0 in windows_); created during Init.
-	ImGuiRenderer renderer_{};
+	std::vector<std::unique_ptr<WindowState> > windows_;
-	SDL_Window *window_   = nullptr;
-	SDL_GLContext gl_ctx_ = nullptr;
-	int width_            = 1280;
-	int height_           = 800;
 };

ImGuiInputHandler.cc

@@ -125,7 +125,11 @@ map_key(const SDL_Keycode key,
 	case SDLK_KP_ENTER:
 		k_prefix = false;
 		k_ctrl_pending = false;
+		if (mod & KMOD_SHIFT) {
+			out = {true, CommandId::SmartNewline, "", 0};
+		} else {
 			out = {true, CommandId::Newline, "", 0};
+		}
 		return true;
 	case SDLK_ESCAPE:
 		k_prefix = false;
@@ -333,6 +337,38 @@ ImGuiInputHandler::ProcessSDLEvent(const SDL_Event &e)
 		SDL_Keymod mods         = SDL_Keymod(e.key.keysym.mod);
 		const SDL_Keycode key   = e.key.keysym.sym;
 
+		// New window: Cmd+N (macOS) or Ctrl+Shift+N (Linux/Windows)
+		{
+			const bool gui_n   = (mods & KMOD_GUI) && !(mods & KMOD_CTRL) && (key == SDLK_n);
+			const bool ctrl_sn = (mods & KMOD_CTRL) && (mods & KMOD_SHIFT) && (key == SDLK_n);
+			if (gui_n || ctrl_sn) {
+				std::lock_guard<std::mutex> lk(mu_);
+				q_.push(MappedInput{true, CommandId::NewWindow, std::string(), 0});
+				suppress_text_input_once_ = true;
+				return true;
+			}
+		}
+
+		// Font zoom: Cmd+=/Cmd+-/Cmd+0 (macOS) or Ctrl+=/Ctrl+-/Ctrl+0
+		if ((mods & (KMOD_CTRL | KMOD_GUI)) && !(mods & KMOD_SHIFT)) {
+			bool is_zoom = true;
+			CommandId zoom_cmd = CommandId::FontZoomIn;
+			if (key == SDLK_EQUALS || key == SDLK_PLUS)
+				zoom_cmd = CommandId::FontZoomIn;
+			else if (key == SDLK_MINUS)
+				zoom_cmd = CommandId::FontZoomOut;
+			else if (key == SDLK_0)
+				zoom_cmd = CommandId::FontZoomReset;
+			else
+				is_zoom = false;
+			if (is_zoom) {
+				std::lock_guard<std::mutex> lk(mu_);
+				q_.push(MappedInput{true, zoom_cmd, std::string(), 0});
+				suppress_text_input_once_ = true;
+				return true;
+			}
+		}
+
 		// Handle Paste: Ctrl+V (Windows/Linux) or Cmd+V (macOS)
 		// Note: SDL defines letter keycodes in lowercase only (e.g., SDLK_v). Shift does not change keycode.
 		if ((mods & (KMOD_CTRL | KMOD_GUI)) && (key == SDLK_v)) {
@@ -439,12 +475,14 @@ ImGuiInputHandler::ProcessSDLEvent(const SDL_Event &e)
 		}
 
 		// If editor universal argument is active, consume digit TEXTINPUT
-		if (ed_ && ed_
+		if (ed_ &&ed_
+
 
 		
 		->
 		UArg() != 0
-		) {
+		)
+		{
 			const char *txt = e.text.text;
 			if (txt && *txt) {
 				unsigned char c0 = static_cast<unsigned char>(txt[0]);

ImGuiRenderer.cc

@@ -76,23 +76,18 @@ ImGuiRenderer::Draw(Editor &ed)
 		// Two-way sync between Buffer::Rowoffs and ImGui scroll position:
 		// - If command layer changed Buffer::Rowoffs since last frame, drive ImGui scroll from it.
 		// - Otherwise, propagate ImGui scroll to Buffer::Rowoffs so command layer has an up-to-date view.
-		static long prev_buf_rowoffs = -1; // previous frame's Buffer::Rowoffs
-		static long prev_buf_coloffs = -1; // previous frame's Buffer::Coloffs
-
 		const long buf_rowoffs = static_cast<long>(buf->Rowoffs());
 		const long buf_coloffs = static_cast<long>(buf->Coloffs());
 
 		// Detect programmatic change (e.g., page_down command changed rowoffs)
 		// Use SetNextWindowScroll BEFORE BeginChild to set initial scroll position
-		if (prev_buf_rowoffs >= 0 && buf_rowoffs != prev_buf_rowoffs) {
+		if (prev_buf_rowoffs_ >= 0 && buf_rowoffs != prev_buf_rowoffs_) {
 			float target_y = static_cast<float>(buf_rowoffs) * row_h;
 			ImGui::SetNextWindowScroll(ImVec2(-1.0f, target_y));
 		}
-		if (prev_buf_coloffs >= 0 && buf_coloffs != prev_buf_coloffs) {
+		// Horizontal scroll is handled purely in pixel space (see
-			float target_x = static_cast<float>(buf_coloffs) * space_w;
+		// cursor-visibility block after the line loop) so we don't
-			float target_y = static_cast<float>(buf_rowoffs) * row_h;
+		// convert the character-based coloffs to an ImGui scroll here.
-			ImGui::SetNextWindowScroll(ImVec2(target_x, target_y));
-		}
 
 		// Reserve space for status bar at bottom.
 		// We calculate a height that is an exact multiple of the line height
@@ -111,44 +106,92 @@ ImGuiRenderer::Draw(Editor &ed)
 		ImVec2 child_window_pos = ImGui::GetWindowPos();
 		float scroll_y          = ImGui::GetScrollY();
 		float scroll_x          = ImGui::GetScrollX();
-		std::size_t rowoffs     = 0; // we render from the first line; scrolling is handled by ImGui
 
 		// Synchronize buffer offsets from ImGui scroll if user scrolled manually
 		bool forced_scroll = false;
 		{
-			static float prev_scroll_y = -1.0f; // previous frame's ImGui scroll Y in pixels
-			static float prev_scroll_x = -1.0f; // previous frame's ImGui scroll X in pixels
-
 			const long scroll_top  = static_cast<long>(scroll_y / row_h);
-			const long scroll_left = static_cast<long>(scroll_x / space_w);
 
 			// Check if rowoffs was programmatically changed this frame
-			if (prev_buf_rowoffs >= 0 && buf_rowoffs != prev_buf_rowoffs) {
+			if (prev_buf_rowoffs_ >= 0 && buf_rowoffs != prev_buf_rowoffs_) {
 				forced_scroll = true;
 			}
 
-			// If user scrolled (not programmatic), update buffer offsets accordingly
+			// If user scrolled vertically (not programmatic), update buffer row offset
-			if (prev_scroll_y >= 0.0f && scroll_y != prev_scroll_y && !forced_scroll) {
+			if (prev_scroll_y_ >= 0.0f && scroll_y != prev_scroll_y_ && !forced_scroll) {
 				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
 					mbuf->SetOffsets(static_cast<std::size_t>(std::max(0L, scroll_top)),
 					                 mbuf->Coloffs());
 				}
 			}
-			if (prev_scroll_x >= 0.0f && scroll_x != prev_scroll_x && !forced_scroll) {
+			// Horizontal scroll is pixel-based and managed by the cursor
-				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
+			// visibility block below; we don't sync it back to coloffs.
-					mbuf->SetOffsets(mbuf->Rowoffs(),
+
-					                 static_cast<std::size_t>(std::max(0L, scroll_left)));
+			// Update trackers for next frame
+			prev_scroll_y_ = scroll_y;
+			prev_scroll_x_ = scroll_x;
+		}
+		prev_buf_rowoffs_ = buf_rowoffs;
+		prev_buf_coloffs_ = buf_coloffs;
+
+		// Max-line-width cache: reset when the buffer or font changes. We only
+		// measure visible lines per frame and maintain a running max, so the
+		// scrollbar may be slightly conservative on first view of a file until
+		// the user scrolls, but idle CPU drops dramatically on large files.
+		// Edits bump the buffer version but we intentionally do NOT reset the
+		// max on version changes — keeping a conservative (possibly too-wide)
+		// scrollbar is preferable to per-keystroke jitter.
+		{
+			ImFont *cur_font = ImGui::GetFont();
+			float cur_fsize  = ImGui::GetFontSize();
+			if (buf != max_width_buf_
+			    || cur_font != max_width_font_
+			    || cur_fsize != max_width_font_size_) {
+				max_width_buf_       = buf;
+				max_width_font_      = cur_font;
+				max_width_font_size_ = cur_fsize;
+				max_width_px_        = 0.0f;
+			}
+			max_width_version_ = buf->Version();
+		}
+
+		// Hoist the search-regex compilation out of the per-line loop. Compiling
+		// std::regex per line per frame was a large source of idle CPU on macOS.
+		const bool search_mode = ed.SearchActive() && !ed.SearchQuery().empty();
+		const bool regex_mode  = search_mode && ed.PromptActive() && (
+			ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch ||
+			ed.CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind);
+		std::regex search_rx;
+		bool search_rx_valid = false;
+		if (regex_mode) {
+			try {
+				search_rx       = std::regex(ed.SearchQuery());
+				search_rx_valid = true;
+			} catch (const std::regex_error &) {
+				search_rx_valid = false;
 			}
 		}
 
-			// Update trackers for next frame
+		// Compute the visible row range and skip rendering work for off-screen
-			prev_scroll_y = scroll_y;
+		// lines. ImGui clips drawing, but string allocation, tab expansion,
-			prev_scroll_x = scroll_x;
+		// syntax-highlight lookups, and width measurement are not free.
+		const std::size_t total_rows = lines.size();
+		std::size_t first_vis = 0;
+		std::size_t last_vis  = total_rows; // exclusive
+		if (row_h > 0.0f && total_rows > 0) {
+			const long margin = 4; // render a few extra rows above/below for smoother scrolling
+			long fv           = static_cast<long>(std::floor(scroll_y / row_h)) - margin;
+			long lv           = static_cast<long>(
+				std::ceil((scroll_y + child_h_plan) / row_h)) + margin;
+			if (fv < 0) fv = 0;
+			if (lv < 0) lv = 0;
+			if (static_cast<std::size_t>(fv) > total_rows)
+				fv = static_cast<long>(total_rows);
+			if (static_cast<std::size_t>(lv) > total_rows)
+				lv = static_cast<long>(total_rows);
+			first_vis = static_cast<std::size_t>(fv);
+			last_vis  = static_cast<std::size_t>(lv);
 		}
-		prev_buf_rowoffs = buf_rowoffs;
-		prev_buf_coloffs = buf_coloffs;
-		// Cache current horizontal offset in rendered columns for click handling
-		const std::size_t coloffs_now = buf->Coloffs();
 
 		// Mark selection state (mark -> cursor), in source coordinates
 		bool sel_active    = false;
@@ -169,7 +212,7 @@ ImGuiRenderer::Draw(Editor &ed)
 		const std::size_t vsel_sy = vsel_active ? buf->VisualLineStartY() : 0;
 		const std::size_t vsel_ey = vsel_active ? buf->VisualLineEndY() : 0;
 
-		static bool mouse_selecting = false;
+		// (mouse_selecting__ is a member variable)
 		auto mouse_pos_to_buf       = [&]() -> std::pair<std::size_t, std::size_t> {
 			ImVec2 mp = ImGui::GetIO().MousePos;
 			// Convert mouse pos to buffer row
@@ -181,75 +224,142 @@ ImGuiRenderer::Draw(Editor &ed)
 			if (by >= lines.size())
 				by = lines.empty() ? 0 : (lines.size() - 1);
 
-			// Convert mouse pos to rendered x
+			if (lines.empty())
+				return {0, 0};
+
+			// Expand tabs for the clicked line
+			std::string line_clicked = static_cast<std::string>(lines[by]);
+			const std::size_t tabw   = 8;
+			std::string click_expanded;
+			click_expanded.reserve(line_clicked.size() + 16);
+			std::size_t click_rx = 0;
+			// Map: source column -> expanded column
+			std::vector<std::size_t> src_to_exp;
+			src_to_exp.reserve(line_clicked.size() + 1);
+			for (std::size_t ci = 0; ci < line_clicked.size(); ++ci) {
+				src_to_exp.push_back(click_rx);
+				if (line_clicked[ci] == '\t') {
+					std::size_t adv = (tabw - (click_rx % tabw));
+					click_expanded.append(adv, ' ');
+					click_rx += adv;
+				} else {
+					click_expanded.push_back(line_clicked[ci]);
+					click_rx += 1;
+				}
+			}
+			src_to_exp.push_back(click_rx); // past-end position
+
+			// Pixel x relative to the line start (accounting for scroll)
 			float visual_x = mp.x - child_window_pos.x;
 			if (visual_x < 0.0f)
 				visual_x = 0.0f;
-			std::size_t clicked_rx = static_cast<std::size_t>(visual_x / space_w) + coloffs_now;
+			// Add scroll offset in pixels
+			visual_x += scroll_x;
 
-			// Convert rendered column to source column
+			// Find the source column whose expanded position is closest
-			if (lines.empty())
+			// to the click pixel, using actual text measurement.
-				return {0, 0};
-			std::string line_clicked = static_cast<std::string>(lines[by]);
-			const std::size_t tabw   = 8;
-			std::size_t rx           = 0;
 			std::size_t best_col  = 0;
 			float best_dist       = std::numeric_limits<float>::infinity();
-			float clicked_rx_f       = static_cast<float>(clicked_rx);
+			for (std::size_t ci = 0; ci <= line_clicked.size(); ++ci) {
-			for (std::size_t i = 0; i <= line_clicked.size(); ++i) {
+				std::size_t exp_col = src_to_exp[ci];
-				float dist = std::fabs(clicked_rx_f - static_cast<float>(rx));
+				float px = 0.0f;
+				if (exp_col > 0 && !click_expanded.empty()) {
+					std::size_t end = std::min(click_expanded.size(), exp_col);
+					px = ImGui::CalcTextSize(click_expanded.c_str(),
+					                         click_expanded.c_str() + end).x;
+				}
+				float dist = std::fabs(visual_x - px);
 				if (dist < best_dist) {
 					best_dist = dist;
-					best_col  = i;
+					best_col  = ci;
-				}
-				if (i < line_clicked.size()) {
-					rx += (line_clicked[i] == '\t') ? (tabw - (rx % tabw)) : 1;
 				}
 			}
 			return {by, best_col};
 		};
 
-		// Mouse-driven selection: set mark on press, update cursor on drag
+		// Mouse-driven selection: set mark on double-click or drag, update cursor on any press/drag
 		if (ImGui::IsWindowHovered() && ImGui::IsMouseClicked(ImGuiMouseButton_Left)) {
-			mouse_selecting = true;
+			mouse_selecting_ = true;
 			auto [by, bx]   = mouse_pos_to_buf();
 			char tmp[64];
 			std::snprintf(tmp, sizeof(tmp), "%zu:%zu", by, bx);
 			Execute(ed, CommandId::MoveCursorTo, std::string(tmp));
+
+			// Only set mark on double click.
+			// Dragging will also set the mark if not already set (handled below).
+			if (ImGui::IsMouseDoubleClicked(ImGuiMouseButton_Left)) {
 				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
 					mbuf->SetMark(bx, by);
 				}
 			}
-		if (mouse_selecting && ImGui::IsWindowHovered() && ImGui::IsMouseDown(ImGuiMouseButton_Left)) {
+		}
+		if (mouse_selecting_ && ImGui::IsWindowHovered() && ImGui::IsMouseDown(ImGuiMouseButton_Left)) {
 			auto [by, bx] = mouse_pos_to_buf();
+			// If we are dragging (mouse moved while down), ensure mark is set to start selection
+			if (ImGui::IsMouseDragging(ImGuiMouseButton_Left, 1.0f)) {
+				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
+					if (!mbuf->MarkSet()) {
+						// We'd need to convert click_pos to buf coords, but it's complex here.
+						// Setting it to where the cursor was *before* we started moving it
+						// in this frame is a good approximation, or just using current.
+						mbuf->SetMark(mbuf->Curx(), mbuf->Cury());
+					}
+				}
+			}
 			char tmp[64];
 			std::snprintf(tmp, sizeof(tmp), "%zu:%zu", by, bx);
 			Execute(ed, CommandId::MoveCursorTo, std::string(tmp));
 		}
-		if (mouse_selecting && ImGui::IsMouseReleased(ImGuiMouseButton_Left)) {
+		if (mouse_selecting_ && ImGui::IsMouseReleased(ImGuiMouseButton_Left)) {
-			mouse_selecting = false;
+			mouse_selecting_ = false;
 		}
-		for (std::size_t i = rowoffs; i < lines.size(); ++i) {
+		// Advance the cursor Y so the first visible line draws at its correct
+		// scroll position. Skipped rows simply leave the layout cursor untouched.
+		if (first_vis > 0) {
+			ImGui::SetCursorPosY(ImGui::GetCursorPosY() +
+			                     static_cast<float>(first_vis) * row_h);
+		}
+		for (std::size_t i = first_vis; i < last_vis; ++i) {
 			// Capture the screen position before drawing the line
 			ImVec2 line_pos  = ImGui::GetCursorScreenPos();
 			std::string line = static_cast<std::string>(lines[i]);
 
-			// Expand tabs to spaces with width=8 and apply horizontal scroll offset
+			// Expand tabs to spaces with width=8
 			const std::size_t tabw = 8;
 			std::string expanded;
 			expanded.reserve(line.size() + 16);
-			std::size_t rx_abs_draw = 0; // rendered column for drawing
+			std::size_t rx_abs_draw = 0;
+			for (std::size_t src = 0; src < line.size(); ++src) {
+				char c = line[src];
+				if (c == '\t') {
+					std::size_t adv = (tabw - (rx_abs_draw % tabw));
+					expanded.append(adv, ' ');
+					rx_abs_draw += adv;
+				} else {
+					expanded.push_back(c);
+					rx_abs_draw += 1;
+				}
+			}
+
+			// Helper: convert a rendered column position to an absolute
+			// pixel x offset from the start of the line.  ImGui's scroll
+			// handles viewport clipping so we measure from column 0.
+			auto rx_to_px = [&](std::size_t rx_col) -> float {
+				std::size_t end = std::min(expanded.size(), rx_col);
+				if (end == 0)
+					return 0.0f;
+				return ImGui::CalcTextSize(expanded.c_str(),
+				                           expanded.c_str() + end).x;
+			};
+
 			// Compute search highlight ranges for this line in source indices
-			bool search_mode = ed.SearchActive() && !ed.SearchQuery().empty();
 			std::vector<std::pair<std::size_t, std::size_t> > hl_src_ranges;
 			if (search_mode) {
-				// If we're in RegexSearch or RegexReplaceFind mode, compute ranges using regex; otherwise plain substring
+				// In regex mode, reuse the compiled regex hoisted above the loop.
-				if (ed.PromptActive() && (
+				if (regex_mode) {
-					    ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.
+					if (search_rx_valid) {
-					    CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
 						try {
-						std::regex rx(ed.SearchQuery());
+							for (auto it = std::sregex_iterator(line.begin(), line.end(), search_rx);
-						for (auto it = std::sregex_iterator(line.begin(), line.end(), rx);
 							     it != std::sregex_iterator(); ++it) {
 								const auto &m  = *it;
 								std::size_t sx = static_cast<std::size_t>(m.position());
@@ -259,6 +369,7 @@ ImGuiRenderer::Draw(Editor &ed)
 						} catch (const std::regex_error &) {
 							// ignore invalid patterns here; status line already shows the error
 						}
+					}
 				} else {
 					const std::string &q = ed.SearchQuery();
 					std::size_t pos      = 0;
@@ -290,13 +401,8 @@ ImGuiRenderer::Draw(Editor &ed)
 					std::size_t sx       = rg.first, ex = rg.second;
 					std::size_t rx_start = src_to_rx(sx);
 					std::size_t rx_end   = src_to_rx(ex);
-					// Apply horizontal scroll offset
+					ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start), line_pos.y);
-					if (rx_end <= coloffs_now)
+					ImVec2 p1 = ImVec2(line_pos.x + rx_to_px(rx_end),
-						continue; // fully left of view
-					std::size_t vx0 = (rx_start > coloffs_now) ? (rx_start - coloffs_now) : 0;
-					std::size_t vx1 = rx_end - coloffs_now;
-					ImVec2 p0 = ImVec2(line_pos.x + static_cast<float>(vx0) * space_w, line_pos.y);
-					ImVec2 p1 = ImVec2(line_pos.x + static_cast<float>(vx1) * space_w,
 					                   line_pos.y + line_h);
 					// Choose color: current match stronger
 					bool is_current = has_current && sx == cur_x && ex == cur_end;
@@ -333,20 +439,14 @@ ImGuiRenderer::Draw(Editor &ed)
 				if (line_has) {
 					std::size_t rx_start = src_to_rx(sx);
 					std::size_t rx_end   = src_to_rx(ex);
-					if (rx_end > coloffs_now) {
+					ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start),
-						std::size_t vx0 = (rx_start > coloffs_now)
-							                  ? (rx_start - coloffs_now)
-							                  : 0;
-						std::size_t vx1 = rx_end - coloffs_now;
-						ImVec2 p0       = ImVec2(line_pos.x + static_cast<float>(vx0) * space_w,
 					                   line_pos.y);
-						ImVec2 p1 = ImVec2(line_pos.x + static_cast<float>(vx1) * space_w,
+					ImVec2 p1 = ImVec2(line_pos.x + rx_to_px(rx_end),
 					                   line_pos.y + line_h);
 					ImU32 col = ImGui::GetColorU32(ImGuiCol_TextSelectedBg);
 					ImGui::GetWindowDrawList()->AddRectFilled(p0, p1, col);
 				}
 			}
-			}
 			if (vsel_active && i >= vsel_sy && i <= vsel_ey) {
 				// Visual-line (multi-cursor) mode: highlight only the per-line cursor spot.
 				const std::size_t spot_sx  = std::min(buf->Curx(), line.size());
@@ -358,32 +458,13 @@ ImGuiRenderer::Draw(Editor &ed)
 					// EOL spot: draw a 1-cell highlight just past the last character.
 					rx_end = rx_start + 1;
 				}
-				if (rx_end > coloffs_now) {
+				ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start),
-					std::size_t vx0 = (rx_start > coloffs_now)
-						                  ? (rx_start - coloffs_now)
-						                  : 0;
-					std::size_t vx1 = rx_end - coloffs_now;
-					ImVec2 p0       = ImVec2(line_pos.x + static_cast<float>(vx0) * space_w,
 				                   line_pos.y);
-					ImVec2 p1 = ImVec2(line_pos.x + static_cast<float>(vx1) * space_w,
+				ImVec2 p1 = ImVec2(line_pos.x + rx_to_px(rx_end),
 				                   line_pos.y + line_h);
 				ImU32 col = ImGui::GetColorU32(ImGuiCol_TextSelectedBg);
 				ImGui::GetWindowDrawList()->AddRectFilled(p0, p1, col);
 			}
-			}
-			// Emit entire line to an expanded buffer (tabs -> spaces)
-			for (std::size_t src = 0; src < line.size(); ++src) {
-				char c = line[src];
-				if (c == '\t') {
-					std::size_t adv = (tabw - (rx_abs_draw % tabw));
-					expanded.append(adv, ' ');
-					rx_abs_draw += adv;
-				} else {
-					expanded.push_back(c);
-					rx_abs_draw += 1;
-				}
-			}
-
 			// Draw syntax-colored runs (text above background highlights)
 			if (buf->SyntaxEnabled() && buf->Highlighter() && buf->Highlighter()->HasHighlighter()) {
 				kte::LineHighlight lh = buf->Highlighter()->GetLine(
@@ -426,19 +507,14 @@ ImGuiRenderer::Draw(Editor &ed)
 				for (const auto &sp: spans) {
 					std::size_t rx_s = src_to_rx_full(sp.s);
 					std::size_t rx_e = src_to_rx_full(sp.e);
-					if (rx_e <= coloffs_now)
+					std::size_t draw_start = rx_s;
-						continue; // fully left of viewport
-					// Clamp to visible portion and expanded length
-					std::size_t draw_start = (rx_s > coloffs_now) ? rx_s : coloffs_now;
 					if (draw_start >= expanded.size())
-						continue; // fully right of expanded text
+						continue;
 					std::size_t draw_end = std::min<std::size_t>(rx_e, expanded.size());
 					if (draw_end <= draw_start)
 						continue;
-					// Screen position is relative to coloffs_now
-					std::size_t screen_x = draw_start - coloffs_now;
 					ImU32 col = ImGui::GetColorU32(kte::SyntaxInk(sp.k));
-					ImVec2 p = ImVec2(line_pos.x + static_cast<float>(screen_x) * space_w,
+					ImVec2 p = ImVec2(line_pos.x + rx_to_px(draw_start),
 					                  line_pos.y);
 					ImGui::GetWindowDrawList()->AddText(
 						p, col, expanded.c_str() + draw_start, expanded.c_str() + draw_end);
@@ -447,49 +523,49 @@ ImGuiRenderer::Draw(Editor &ed)
 				// Use row_h (with spacing) to match click calculation and ensure consistent line positions.
 				ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + row_h));
 			} else {
-				// No syntax: draw as one run, accounting for horizontal scroll offset
+				// No syntax: draw the full line; ImGui scroll handles clipping.
-				if (coloffs_now < expanded.size()) {
+				if (!expanded.empty()) {
 					ImVec2 p = ImVec2(line_pos.x, line_pos.y);
 					ImGui::GetWindowDrawList()->AddText(
 						p, ImGui::GetColorU32(ImGuiCol_Text),
-						expanded.c_str() + coloffs_now);
+						expanded.c_str());
-					ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + row_h));
-				} else {
-					// Line is fully scrolled out of view horizontally
-					ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + row_h));
 				}
+				ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + row_h));
 			}
 
 			// Draw a visible cursor indicator on the current line
 			if (i == cy) {
-				// Compute rendered X (rx) from source column with tab expansion
+				std::size_t rx_abs = src_to_rx(cx);
-				std::size_t rx_abs = 0;
+				float cursor_px = rx_to_px(rx_abs);
-				for (std::size_t k = 0; k < std::min(cx, line.size()); ++k) {
-					if (line[k] == '\t')
-						rx_abs += (tabw - (rx_abs % tabw));
-					else
-						rx_abs += 1;
-				}
-				// Convert to viewport x by subtracting horizontal col offset
-				std::size_t rx_viewport = (rx_abs > coloffs_now) ? (rx_abs - coloffs_now) : 0;
-				// For proportional fonts (Linux GUI), avoid accumulating drift by computing
-				// the exact pixel width of the expanded substring up to the cursor.
-				// expanded contains the line with tabs expanded to spaces and is what we draw.
-				float cursor_px = 0.0f;
-				if (rx_viewport > 0 && coloffs_now < expanded.size()) {
-					std::size_t start = coloffs_now;
-					std::size_t end   = std::min(expanded.size(), start + rx_viewport);
-					// Measure substring width in pixels
-					ImVec2 sz = ImGui::CalcTextSize(expanded.c_str() + start,
-					                                expanded.c_str() + end);
-					cursor_px = sz.x;
-				}
 				ImVec2 p0 = ImVec2(line_pos.x + cursor_px, line_pos.y);
 				ImVec2 p1 = ImVec2(p0.x + space_w, p0.y + line_h);
 				ImU32 col = IM_COL32(200, 200, 255, 128); // soft highlight
 				ImGui::GetWindowDrawList()->AddRectFilled(p0, p1, col);
 			}
+
+			// Track widest line for content width reporting. We only measure
+			// visible lines and fold the result into a monotonic max cached on
+			// the renderer (see max_width_* members). Off-screen lines are not
+			// measured per frame; if the user scrolls or edits, the cache is
+			// refreshed accordingly.
+			if (!expanded.empty()) {
+				float line_w = ImGui::CalcTextSize(expanded.c_str()).x;
+				if (line_w > max_width_px_)
+					max_width_px_ = line_w;
 			}
+		}
+		// After the visible-range loop, advance the layout cursor to the end of
+		// the (virtual) content so ImGui sees the correct total size. Vertical
+		// height comes from total_rows; horizontal width comes from the cached
+		// max line width. A Dummy at the final position records both.
+		if (total_rows > last_vis) {
+			ImGui::SetCursorPosY(ImGui::GetCursorPosY() +
+			                     static_cast<float>(total_rows - last_vis) * row_h);
+		}
+		if (max_width_px_ > 0.0f) {
+			ImGui::SetCursorPosX(max_width_px_);
+		}
+		ImGui::Dummy(ImVec2(0, 0));
 		// Synchronize cursor and scrolling after rendering all lines so content size is known.
 		{
 			float child_h_actual = ImGui::GetWindowHeight();
@@ -529,29 +605,40 @@ ImGuiRenderer::Draw(Editor &ed)
 				last_row  = first_row + vis_rows - 1;
 			}
 
-			// Horizontal scroll: ensure cursor column is visible
+			// Horizontal scroll: ensure cursor is visible (pixel-based for proportional fonts)
-			long vis_cols = static_cast<long>(std::round(child_w_actual / space_w));
+			float cursor_px_abs = 0.0f;
-			if (vis_cols < 1)
-				vis_cols = 1;
-			long first_col = static_cast<long>(scroll_x_now / space_w);
-			long last_col  = first_col + vis_cols - 1;
-
-			std::size_t cursor_rx = 0;
 			if (cy < lines.size()) {
 				std::string cur_line   = static_cast<std::string>(lines[cy]);
 				const std::size_t tabw = 8;
-				for (std::size_t i = 0; i < cx && i < cur_line.size(); ++i) {
+				// Expand tabs for cursor line to measure pixel position
-					if (cur_line[i] == '\t') {
+				std::string cur_expanded;
-						cursor_rx += tabw - (cursor_rx % tabw);
+				cur_expanded.reserve(cur_line.size() + 16);
+				std::size_t cur_rx = 0;
+				for (std::size_t ci = 0; ci < cur_line.size(); ++ci) {
+					if (cur_line[ci] == '\t') {
+						std::size_t adv = tabw - (cur_rx % tabw);
+						cur_expanded.append(adv, ' ');
+						cur_rx += adv;
 					} else {
+						cur_expanded.push_back(cur_line[ci]);
+						cur_rx += 1;
+					}
+				}
+				// Compute rendered column of cursor
+				std::size_t cursor_rx = 0;
+				for (std::size_t ci = 0; ci < cx && ci < cur_line.size(); ++ci) {
+					if (cur_line[ci] == '\t')
+						cursor_rx += tabw - (cursor_rx % tabw);
+					else
 						cursor_rx += 1;
 				}
+				std::size_t exp_end = std::min(cur_expanded.size(), cursor_rx);
+				if (exp_end > 0)
+					cursor_px_abs = ImGui::CalcTextSize(cur_expanded.c_str(),
+					                                    cur_expanded.c_str() + exp_end).x;
 			}
-			}
+			if (cursor_px_abs < scroll_x_now || cursor_px_abs > scroll_x_now + child_w_actual) {
-			long cxr = static_cast<long>(cursor_rx);
+				float target_x = cursor_px_abs - (child_w_actual / 2.0f);
-			if (cxr < first_col || cxr > last_col) {
-				float target_x = static_cast<float>(cxr) * space_w;
-				target_x       -= (child_w_actual / 2.0f);
 				if (target_x < 0.f)
 					target_x = 0.f;
 				float max_x = ImGui::GetScrollMaxX();

ImGuiRenderer.h

@@ -2,8 +2,13 @@
  * ImGuiRenderer - ImGui-based renderer for GUI mode
  */
 #pragma once
+#include <cstdint>
+#include <string>
 #include "Renderer.h"
 
+struct ImFont;
+class Buffer;
+
 class ImGuiRenderer final : public Renderer {
 public:
 	ImGuiRenderer() = default;
@@ -11,4 +16,22 @@ public:
 	~ImGuiRenderer() override = default;
 
 	void Draw(Editor &ed) override;
+
+private:
+	// Per-window scroll tracking for two-way sync between Buffer offsets and ImGui scroll.
+	// These must be per-instance (not static) so each window maintains independent state.
+	long prev_buf_rowoffs_ = -1;
+	long prev_buf_coloffs_ = -1;
+	float prev_scroll_y_   = -1.0f;
+	float prev_scroll_x_   = -1.0f;
+	bool mouse_selecting_  = false;
+
+	// Max-line-width cache for the horizontal scrollbar. Measuring every line
+	// every frame is prohibitively expensive on large files; we only update the
+	// running max from visible lines and reset when buffer/version/font changes.
+	const Buffer *max_width_buf_ = nullptr;
+	std::uint64_t max_width_version_ = 0;
+	ImFont *max_width_font_ = nullptr;
+	float max_width_font_size_ = 0.0f;
+	float max_width_px_ = 0.0f;
 };

KKeymap.cc

@@ -84,6 +84,9 @@ KLookupKCommand(const int ascii_key, const bool ctrl, CommandId &out) -> bool
 	case 'l':
 		out = CommandId::ReloadBuffer;
 		return true;
+	case 'm':
+		out = CommandId::ToggleEditMode;
+		return true;
 	case 'n':
 		out = CommandId::BufferPrev;
 		return true;
@@ -226,6 +229,10 @@ KLookupEscCommand(const int ascii_key, CommandId &out) -> bool
 	case 'q':
 		out = CommandId::ReflowParagraph; // Esc q (reflow paragraph)
 		return true;
+	case '\n':
+	case '\r':
+		out = CommandId::SmartNewline; // Shift+Enter (some terminals send this as Alt+Enter sequences)
+		return true;
 	default:
 		break;
 	}

TerminalInputHandler.cc

@@ -67,13 +67,20 @@ map_key_to_command(const int ch,
 				if (pressed) {
 					mouse_selecting = true;
 					Execute(*ed, CommandId::MoveCursorTo, std::string(buf));
-					if (Buffer *b = ed->CurrentBuffer()) {
+					// We don't set the mark on simple click anymore in ncurses either,
-						b->SetMark(b->Curx(), b->Cury());
+					// to be consistent. ncurses doesn't easily support double-click
-					}
+					// or drag-threshold in a platform-independent way here,
+					// but we can at least only set mark on MOVED.
 					out.hasCommand = false;
 					return true;
 				}
 				if (mouse_selecting && moved) {
+					if (Buffer *b = ed->CurrentBuffer()) {
+						if (!b->MarkSet()) {
+							// Set mark at CURRENT cursor position (which is where we were before this move)
+							b->SetMark(b->Curx(), b->Cury());
+						}
+					}
 					Execute(*ed, CommandId::MoveCursorTo, std::string(buf));
 					out.hasCommand = false;
 					return true;

UndoNode.h

@@ -9,6 +9,7 @@ enum class UndoType : std::uint8_t {
 	Paste,
 	Newline,
 	DeleteRow,
+	InsertRow,
 };
 
 struct UndoNode {

UndoSystem.cc

@@ -36,7 +36,8 @@ UndoSystem::Begin(UndoType type)
 	const int col = static_cast<int>(buf_->Curx());
 
 	// Some operations should always be standalone undo steps.
-	const bool always_standalone = (type == UndoType::Newline || type == UndoType::DeleteRow);
+	const bool always_standalone = (type == UndoType::Newline || type == UndoType::DeleteRow || type ==
+	                                UndoType::InsertRow);
 	if (always_standalone) {
 		commit();
 	}
@@ -75,6 +76,7 @@ UndoSystem::Begin(UndoType type)
 			}
 			case UndoType::Newline:
 			case UndoType::DeleteRow:
+			case UndoType::InsertRow:
 				break;
 			}
 		}
@@ -314,6 +316,15 @@ UndoSystem::apply(const UndoNode *node, int direction)
 			buf_->SetCursor(0, static_cast<std::size_t>(node->row));
 		}
 		break;
+	case UndoType::InsertRow:
+		if (direction > 0) {
+			buf_->insert_row(node->row, node->text);
+			buf_->SetCursor(0, static_cast<std::size_t>(node->row));
+		} else {
+			buf_->delete_row(node->row);
+			buf_->SetCursor(0, static_cast<std::size_t>(node->row));
+		}
+		break;
 	}
 }
 
@@ -411,6 +422,8 @@ UndoSystem::type_str(UndoType t)
 		return "Newline";
 	case UndoType::DeleteRow:
 		return "DeleteRow";
+	case UndoType::InsertRow:
+		return "InsertRow";
 	}
 	return "?";
 }

default.nix

@@ -1,6 +1,5 @@
 {
-  pkgs ? import <nixpkgs> {},
+  lib,
-  lib ? pkgs.lib,
   stdenv,
   cmake,
   ncurses,
@@ -10,9 +9,10 @@
   kdePackages,
   qt6Packages ? kdePackages.qt6Packages,
   installShellFiles,
+  copyDesktopItems,
+  makeDesktopItem,
   graphical ? false,
   graphical-qt ? false,
-  ...
 }:
 let
   cmakeContent = builtins.readFile ./CMakeLists.txt;
@@ -23,31 +23,60 @@ let
   version = builtins.head (builtins.match ".*set\\(KTE_VERSION \"(.+)\"\\).*" versionLine);
 in
 stdenv.mkDerivation {
-  pname = "kte";
+  pname = if graphical then (if graphical-qt then "kge-qt" else "kge") else "kte";
   inherit version;
 
   src = lib.cleanSource ./.;
 
   nativeBuildInputs = [
     cmake
-    ncurses
     installShellFiles
-  ]
+  ] ++ lib.optionals graphical [
-  ++ lib.optionals graphical [
+    copyDesktopItems
+  ] ++ lib.optionals graphical-qt [
+    qt6Packages.wrapQtAppsHook
+  ];
+
+  buildInputs = [
+    ncurses
+  ] ++ lib.optionals graphical [
     SDL2
     libGL
     xorg.libX11
-  ]
+  ] ++ lib.optionals graphical-qt [
-  ++ lib.optionals graphical-qt [
     kdePackages.qt6ct
     qt6Packages.qtbase
-    qt6Packages.wrapQtAppsHook
   ];
 
   cmakeFlags = [
     "-DBUILD_GUI=${if graphical then "ON" else "OFF"}"
     "-DKTE_USE_QT=${if graphical-qt then "ON" else "OFF"}"
     "-DCMAKE_BUILD_TYPE=Debug"
+    "-DKTE_STATIC_LINK=OFF"
+  ];
+
+  desktopItems = lib.optionals graphical [
+    (makeDesktopItem {
+      name = "kge";
+      desktopName = "kge";
+      genericName = "Text Editor";
+      comment = "kyle's graphical text editor";
+      exec = if graphical-qt then "kge-qt %F" else "kge %F";
+      icon = "kge";
+      terminal = false;
+      categories = [ "Utility" "TextEditor" "Development" ];
+      mimeTypes = [
+        "text/plain"
+        "text/x-c"
+        "text/x-c++"
+        "text/x-python"
+        "text/x-go"
+        "text/x-rust"
+        "application/json"
+        "text/markdown"
+        "text/x-shellscript"
+      ];
+    })
   ];
 
   installPhase = ''
@@ -58,14 +87,11 @@ stdenv.mkDerivation {
     installManPage ../docs/kte.1
 
     ${lib.optionalString graphical ''
-      mkdir -p $out/bin
-  
       ${if graphical-qt then ''
         cp kge $out/bin/kge-qt
       '' else ''
         cp kge $out/bin/kge
       ''}
-
       installManPage ../docs/kge.1
 
       mkdir -p $out/share/icons/hicolor/256x256/apps
@@ -74,4 +100,10 @@ stdenv.mkDerivation {
 
     runHook postInstall
   '';
+
+  meta = {
+    description = "kyle's text editor" + lib.optionalString graphical " (graphical)";
+    platforms = lib.platforms.unix;
+    mainProgram = if graphical then (if graphical-qt then "kge-qt" else "kge") else "kte";
+  };
 }

docs/themes.md

@@ -23,29 +23,34 @@ Current themes (alphabetically):
 - **gruvbox** — Retro groove color scheme (light/dark variants)
 - **kanagawa-paper** — Inspired by traditional Japanese art
 - **lcars** — Star Trek LCARS interface style
+- **leuchtturm** — Modern, clean theme (light/dark variants)
 - **nord** — Arctic, north-bluish color palette
 - **old-book** — Sepia-toned vintage book aesthetic (light/dark
   variants)
 - **orbital** — Space-themed dark palette
 - **plan9** — Minimalist Plan 9 from Bell Labs inspired
 - **solarized** — Ethan Schoonover's Solarized (light/dark variants)
+- **tufte** — Edward Tufte-inspired minimalist theme (light/dark variants)
 - **weyland-yutani** — Alien franchise corporate aesthetic
 - **zenburn** — Low-contrast, easy-on-the-eyes theme
 
 Configuration
 -------------
 
-Themes are configured via `$HOME/.config/kte/kge.ini`:
+Themes are configured via `$HOME/.config/kte/kge.toml`:
 
-```ini
+```toml
-theme = nord
+[appearance]
-background = dark
+theme = "nord"
+background = "dark"
 ```
 
 - `theme` — The theme name (e.g., "nord", "gruvbox", "solarized")
 - `background` — Either "dark" or "light" (for themes supporting both
   variants)
 
+Legacy `kge.ini` format is also supported (see CONFIG.md).
+
 Themes can also be switched at runtime using the `:theme <name>`
 command.
 

flake.nix

@@ -3,8 +3,7 @@
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 
-  outputs =
+  outputs = { self, nixpkgs, ... }:
-    inputs@{ self, nixpkgs, ... }:
     let
       eachSystem = nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed;
       pkgsFor = system: import nixpkgs { inherit system; };
@@ -17,5 +16,27 @@
         kge = (pkgsFor system).callPackage ./default.nix { graphical = true;  graphical-qt = false; };
         qt  = (pkgsFor system).callPackage ./default.nix { graphical = true;  graphical-qt = true;  };
       });
+
+      devShells = eachSystem (system:
+        let pkgs = pkgsFor system;
+        in {
+          default = pkgs.mkShell {
+            inputsFrom = [ self.packages.${system}.kge ];
+            packages = with pkgs; [ gdb valgrind ];
+          };
+          terminal = pkgs.mkShell {
+            inputsFrom = [ self.packages.${system}.kte ];
+          };
+          qt = pkgs.mkShell {
+            inputsFrom = [ self.packages.${system}.qt ];
+            packages = with pkgs; [ gdb valgrind ];
+          };
+        }
+      );
+
+      overlays.default = final: prev: {
+        kte = self.packages.${final.system}.kte;
+        kge = self.packages.${final.system}.kge;
+      };
     };
 }

fonts/FontList.h

@@ -3,6 +3,8 @@
 #include "BerkeleyMono.h"
 #include "BrassMono.h"
 #include "BrassMonoCode.h"
+#include "CrimsonPro.h"
+#include "ETBook.h"
 #include "FiraCode.h"
 #include "Go.h"
 #include "IBMPlexMono.h"
@@ -13,6 +15,7 @@
 #include "IosevkaExtended.h"
 #include "ShareTech.h"
 #include "SpaceMono.h"
+#include "Spectral.h"
 #include "Syne.h"
 #include "Triplicate.h"
 #include "Unispace.h"

fonts/FontRegistry.cc

@@ -45,6 +45,16 @@ InstallDefaultFonts()
 		BrassMonoCode::DefaultFontBoldCompressedData,
 		BrassMonoCode::DefaultFontBoldCompressedSize
 	));
+	FontRegistry::Instance().Register(std::make_unique<Font>(
+		"crimsonpro",
+		CrimsonPro::DefaultFontRegularCompressedData,
+		CrimsonPro::DefaultFontRegularCompressedSize
+	));
+	FontRegistry::Instance().Register(std::make_unique<Font>(
+		"etbook",
+		ETBook::DefaultFontRegularCompressedData,
+		ETBook::DefaultFontRegularCompressedSize
+	));
 	FontRegistry::Instance().Register(std::make_unique<Font>(
 		"fira",
 		FiraCode::DefaultFontRegularCompressedData,
@@ -95,6 +105,11 @@ InstallDefaultFonts()
 		SpaceMono::DefaultFontRegularCompressedData,
 		SpaceMono::DefaultFontRegularCompressedSize
 	));
+	FontRegistry::Instance().Register(std::make_unique<Font>(
+		"spectral",
+		Spectral::DefaultFontRegularCompressedData,
+		Spectral::DefaultFontRegularCompressedSize
+	));
 	FontRegistry::Instance().Register(std::make_unique<Font>(
 		"syne",
 		Syne::DefaultFontRegularCompressedData,

fonts/FontRegistry.h

@@ -1,10 +1,12 @@
 #pragma once
 
+#include <algorithm>
 #include <cassert>
 #include <memory>
 #include <mutex>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 #include "Font.h"
 
@@ -87,6 +89,19 @@ public:
 	}
 
 
+	// Return all registered font names (sorted)
+	std::vector<std::string> FontNames() const
+	{
+		std::lock_guard lock(mutex_);
+		std::vector<std::string> names;
+		names.reserve(fonts_.size());
+		for (const auto &[name, _] : fonts_)
+			names.push_back(name);
+		std::sort(names.begin(), names.end());
+		return names;
+	}
+
+
 	// Current font name/size as last successfully loaded via LoadFont()
 	std::string CurrentFontName() const
 	{

kge.toml.example

@@ -0,0 +1,24 @@
+# kge configuration
+# Place at ~/.config/kte/kge.toml
+
+[window]
+fullscreen = false
+columns = 80
+rows = 42
+
+[font]
+# Default font and size
+name = "default"
+size = 18.0
+# Font used in code mode (monospace)
+code = "default"
+# Font used in writing mode (proportional) — for .txt, .md, .rst, .org, .tex, etc.
+writing = "crimsonpro"
+
+[appearance]
+theme = "nord"
+# "dark" or "light" for themes with variants
+background = "dark"
+
+[editor]
+syntax = true

main.cc

@@ -12,6 +12,7 @@
 #include <random>
 #include <thread>
 #include <signal.h>
+#include <filesystem>
 #include <string>
 #include <unistd.h>
 #include <sys/stat.h>
@@ -117,6 +118,9 @@ main(int argc, char *argv[])
 {
 	std::setlocale(LC_ALL, "");
 
+	// Ensure the error handler (and its log file) is initialised early.
+	kte::ErrorHandler::Instance();
+
 	Editor editor;
 
 	// CLI parsing using getopt_long
@@ -252,7 +256,18 @@ main(int argc, char *argv[])
 					// Fall through: not a +number, treat as filename starting with '+'
 				}
 
-				const std::string path = arg;
+				// Resolve to absolute path now, before any
+				// chdir (macOS GUI changes CWD to HOME before
+				// deferred opens are processed).
+				std::string path = arg;
+				try {
+					std::filesystem::path p(path);
+					if (p.is_relative()) {
+						path = std::filesystem::absolute(p).string();
+					}
+				} catch (...) {
+					// Fall through with original path
+				}
 				editor.RequestOpenFile(path, pending_line);
 				pending_line = 0; // consumed (if set)
 			}

make-app-release

@@ -15,20 +15,18 @@ sha256sum kge.app.zip
 open .
 cd ..
 
-mkdir -p cmake-build-release-qt
+# Qt build disabled — ImGui frontend is the primary GUI.
-cmake -S . -B cmake-build-release-qt -DBUILD_GUI=ON -DKTE_USE_QT=ON -DCMAKE_BUILD_TYPE=Release -DENABLE_ASAN=OFF
+# mkdir -p cmake-build-release-qt
-
+# cmake -S . -B cmake-build-release-qt -DBUILD_GUI=ON -DKTE_USE_QT=ON -DCMAKE_BUILD_TYPE=Release -DENABLE_ASAN=OFF
-cd cmake-build-release-qt
+#
-make clean
+# cd cmake-build-release-qt
-rm -fr kge.app* kge-qt.app*
+# make clean
-make
+# rm -fr kge.app* kge-qt.app*
-mv -f kge.app kge-qt.app
+# make
-# Use the same Qt's macdeployqt as used for building; ensure it overwrites in-bundle paths
+# mv -f kge.app kge-qt.app
-macdeployqt kge-qt.app -always-overwrite -verbose=3
+# macdeployqt kge-qt.app -always-overwrite -verbose=3
-
+# cmake -DAPP_BUNDLE="$(pwd)/kge-qt.app" -P "${PWD%/*}/cmake/fix_bundle.cmake"
-# Run CMake BundleUtilities fixup to internalize non-Qt dylibs and rewrite install names
+# zip -r kge-qt.app.zip kge-qt.app
-cmake -DAPP_BUNDLE="$(pwd)/kge-qt.app" -P "${PWD%/*}/cmake/fix_bundle.cmake"
+# sha256sum kge-qt.app.zip
-zip -r kge-qt.app.zip kge-qt.app 
+# open .
-sha256sum kge-qt.app.zip
+# cd ..
-open .
-cd ..

make-release

@@ -22,5 +22,6 @@ fi
 
 git tag "${KTE_VERSION}"
 git push && git push --tags
+git push github && git push github --tags
 
 ( ./make-app-release )

tests/test_reflow_undo.cc

@@ -0,0 +1,69 @@
+#include "Test.h"
+
+#include "Buffer.h"
+#include "Command.h"
+#include "Editor.h"
+#include "UndoSystem.h"
+
+#include <string>
+
+
+static std::string
+to_string_rows(const Buffer &buf)
+{
+	std::string out;
+	for (const auto &r: buf.Rows()) {
+		out += static_cast<std::string>(r);
+		out.push_back('\n');
+	}
+	return out;
+}
+
+
+TEST (ReflowUndo)
+{
+	InstallDefaultCommands();
+
+	Editor ed;
+	ed.SetDimensions(24, 80);
+
+	Buffer b;
+	const std::string initial =
+		"This is a very long line that should be reflowed into multiple lines to see if undo works correctly.\n";
+	b.insert_text(0, 0, initial);
+	b.SetCursor(0, 0);
+
+	// Commit initial insertion so it's its own undo step
+	if (auto *u = b.Undo())
+		u->commit();
+
+	ed.AddBuffer(std::move(b));
+
+	Buffer *buf = ed.CurrentBuffer();
+	ASSERT_TRUE(buf != nullptr);
+
+	const std::string original_dump = to_string_rows(*buf);
+
+	// Reflow with small width
+	const int width = 20;
+	ASSERT_TRUE(Execute(ed, "reflow-paragraph", "", width));
+
+	const std::string reflowed_dump = to_string_rows(*buf);
+	ASSERT_TRUE(reflowed_dump != original_dump);
+	ASSERT_TRUE(buf->Rows().size() > 1);
+
+	// Undo reflow
+	ASSERT_TRUE(Execute(ed, "undo", "", 1));
+	const std::string after_undo_dump = to_string_rows(*buf);
+
+	if (after_undo_dump != original_dump) {
+		fprintf(stderr, "Undo failed.\nExpected:\n%s\nGot:\n%s\n", original_dump.c_str(),
+		        after_undo_dump.c_str());
+	}
+	EXPECT_TRUE(after_undo_dump == original_dump);
+
+	// Redo reflow
+	ASSERT_TRUE(Execute(ed, "redo", "", 1));
+	const std::string after_redo_dump = to_string_rows(*buf);
+	EXPECT_TRUE(after_redo_dump == reflowed_dump);
+}

tests/test_smart_newline.cc

@@ -0,0 +1,79 @@
+#include "Test.h"
+#include "Buffer.h"
+#include "Editor.h"
+#include "Command.h"
+#include <string>
+
+
+TEST (SmartNewline_AutoIndent)
+{
+	Editor editor;
+	InstallDefaultCommands();
+	Buffer &buf = editor.Buffers().emplace_back();
+
+	// Set up initial state: "  line1"
+	buf.insert_text(0, 0, "  line1");
+	buf.SetCursor(7, 0); // At end of line
+
+	// Execute SmartNewline
+	bool ok = Execute(editor, CommandId::SmartNewline);
+	ASSERT_TRUE(ok);
+
+	// Should have two lines now
+	ASSERT_EQ(buf.Nrows(), 2);
+	// Line 0 remains "  line1"
+	ASSERT_EQ(buf.GetLineString(0), "  line1");
+	// Line 1 should have "  " (two spaces)
+	ASSERT_EQ(buf.GetLineString(1), "  ");
+	// Cursor should be at (2, 1)
+	ASSERT_EQ(buf.Curx(), 2);
+	ASSERT_EQ(buf.Cury(), 1);
+}
+
+
+TEST (SmartNewline_TabIndent)
+{
+	Editor editor;
+	InstallDefaultCommands();
+	Buffer &buf = editor.Buffers().emplace_back();
+
+	// Set up initial state: "\tline1"
+	buf.insert_text(0, 0, "\tline1");
+	buf.SetCursor(6, 0); // At end of line
+
+	// Execute SmartNewline
+	bool ok = Execute(editor, CommandId::SmartNewline);
+	ASSERT_TRUE(ok);
+
+	// Should have two lines now
+	ASSERT_EQ(buf.Nrows(), 2);
+	// Line 1 should have "\t"
+	ASSERT_EQ(buf.GetLineString(1), "\t");
+	// Cursor should be at (1, 1)
+	ASSERT_EQ(buf.Curx(), 1);
+	ASSERT_EQ(buf.Cury(), 1);
+}
+
+
+TEST (SmartNewline_NoIndent)
+{
+	Editor editor;
+	InstallDefaultCommands();
+	Buffer &buf = editor.Buffers().emplace_back();
+
+	// Set up initial state: "line1"
+	buf.insert_text(0, 0, "line1");
+	buf.SetCursor(5, 0); // At end of line
+
+	// Execute SmartNewline
+	bool ok = Execute(editor, CommandId::SmartNewline);
+	ASSERT_TRUE(ok);
+
+	// Should have two lines now
+	ASSERT_EQ(buf.Nrows(), 2);
+	// Line 1 should be empty
+	ASSERT_EQ(buf.GetLineString(1), "");
+	// Cursor should be at (0, 1)
+	ASSERT_EQ(buf.Curx(), 0);
+	ASSERT_EQ(buf.Cury(), 1);
+}

tests/test_swap_cleanup2.cc

@@ -0,0 +1,125 @@
+#include "Test.h"
+
+#include "Command.h"
+#include "Editor.h"
+
+#include "tests/TestHarness.h"
+
+#include <cstdio>
+#include <cstdlib>
+#include <filesystem>
+#include <fstream>
+#include <string>
+#include <unistd.h>
+
+namespace fs = std::filesystem;
+
+
+static void
+write_file_bytes(const std::string &path, const std::string &bytes)
+{
+	std::ofstream out(path, std::ios::binary | std::ios::trunc);
+	out.write(bytes.data(), (std::streamsize) bytes.size());
+}
+
+
+// RAII helper to set XDG_STATE_HOME for the duration of a test and clean up.
+struct XdgStateGuard {
+	fs::path root;
+	std::string old_xdg;
+	bool had_old;
+
+	explicit XdgStateGuard(const std::string &suffix)
+	{
+		root = fs::temp_directory_path() /
+		       (std::string("kte_ut_xdg_") + suffix + "_" + std::to_string((int) ::getpid()));
+		fs::remove_all(root);
+		fs::create_directories(root);
+
+		const char *p = std::getenv("XDG_STATE_HOME");
+		had_old       = (p != nullptr);
+		if (p)
+			old_xdg = p;
+		setenv("XDG_STATE_HOME", root.string().c_str(), 1);
+	}
+
+	~XdgStateGuard()
+	{
+		if (had_old)
+			setenv("XDG_STATE_HOME", old_xdg.c_str(), 1);
+		else
+			unsetenv("XDG_STATE_HOME");
+		fs::remove_all(root);
+	}
+};
+
+
+TEST(SwapCleanup_SaveAndQuit)
+{
+	ktet::InstallDefaultCommandsOnce();
+	XdgStateGuard xdg("save_quit");
+
+	const std::string path = (xdg.root / "work" / "file.txt").string();
+	fs::create_directories(xdg.root / "work");
+	write_file_bytes(path, "hello\n");
+
+	Editor ed;
+	ed.SetDimensions(24, 80);
+	ed.AddBuffer(Buffer());
+	std::string err;
+	ASSERT_TRUE(ed.OpenFile(path, err));
+	Buffer *b = ed.CurrentBuffer();
+	ASSERT_TRUE(b != nullptr);
+
+	// Edit to create swap file
+	ASSERT_TRUE(Execute(ed, CommandId::MoveFileStart));
+	ASSERT_TRUE(Execute(ed, CommandId::InsertText, "Z"));
+	ASSERT_TRUE(b->Dirty());
+
+	ed.Swap()->Flush(b);
+	const std::string swp = kte::SwapManager::ComputeSwapPathForTests(*b);
+	ASSERT_TRUE(fs::exists(swp));
+
+	// Save-and-quit should clean up the swap file
+	ASSERT_TRUE(Execute(ed, CommandId::SaveAndQuit));
+	ed.Swap()->Flush(b);
+	ASSERT_TRUE(!fs::exists(swp));
+
+	// Cleanup
+	std::remove(path.c_str());
+}
+
+
+TEST(SwapCleanup_EditorReset)
+{
+	ktet::InstallDefaultCommandsOnce();
+	XdgStateGuard xdg("editor_reset");
+
+	const std::string path = (xdg.root / "work" / "file.txt").string();
+	fs::create_directories(xdg.root / "work");
+	write_file_bytes(path, "hello\n");
+
+	Editor ed;
+	ed.SetDimensions(24, 80);
+	ed.AddBuffer(Buffer());
+	std::string err;
+	ASSERT_TRUE(ed.OpenFile(path, err));
+	Buffer *b = ed.CurrentBuffer();
+	ASSERT_TRUE(b != nullptr);
+
+	// Edit to create swap file
+	ASSERT_TRUE(Execute(ed, CommandId::MoveFileStart));
+	ASSERT_TRUE(Execute(ed, CommandId::InsertText, "W"));
+	ASSERT_TRUE(b->Dirty());
+
+	ed.Swap()->Flush(b);
+	const std::string swp = kte::SwapManager::ComputeSwapPathForTests(*b);
+	ASSERT_TRUE(fs::exists(swp));
+
+	// Reset (simulates clean editor exit) should remove swap files
+	ed.Reset();
+	ASSERT_TRUE(!fs::exists(swp));
+
+	// Cleanup
+	std::remove(path.c_str());
+}

tests/test_swap_edge_cases.cc

@@ -5,6 +5,7 @@
 
 #include <cstdint>
 #include <cstdio>
+#include <cstring>
 #include <fstream>
 #include <string>
 #include <vector>

tests/test_undo.cc

@@ -57,7 +57,7 @@ validate_undo_tree(const UndoSystem &u)
 // The undo suite aims to cover invariants with a small, adversarial test matrix.
 
 
-TEST(Undo_InsertRun_Coalesces_OneStep)
+TEST (Undo_InsertRun_Coalesces_OneStep)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -81,7 +81,7 @@ TEST(Undo_InsertRun_Coalesces_OneStep)
 }
 
 
-TEST(Undo_InsertRun_BreaksOnNonAdjacentCursor)
+TEST (Undo_InsertRun_BreaksOnNonAdjacentCursor)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -109,7 +109,7 @@ TEST(Undo_InsertRun_BreaksOnNonAdjacentCursor)
 }
 
 
-TEST(Undo_BackspaceRun_Coalesces_OneStep)
+TEST (Undo_BackspaceRun_Coalesces_OneStep)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -143,7 +143,7 @@ TEST(Undo_BackspaceRun_Coalesces_OneStep)
 }
 
 
-TEST(Undo_DeleteKeyRun_Coalesces_OneStep)
+TEST (Undo_DeleteKeyRun_Coalesces_OneStep)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -176,7 +176,7 @@ TEST(Undo_DeleteKeyRun_Coalesces_OneStep)
 }
 
 
-TEST(Undo_Newline_IsStandalone)
+TEST (Undo_Newline_IsStandalone)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -211,7 +211,7 @@ TEST(Undo_Newline_IsStandalone)
 }
 
 
-TEST(Undo_ExplicitGroup_UndoesAsUnit)
+TEST (Undo_ExplicitGroup_UndoesAsUnit)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -239,7 +239,7 @@ TEST(Undo_ExplicitGroup_UndoesAsUnit)
 }
 
 
-TEST(Undo_Branching_RedoBranchSelectionDeterministic)
+TEST (Undo_Branching_RedoBranchSelectionDeterministic)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -283,7 +283,7 @@ TEST(Undo_Branching_RedoBranchSelectionDeterministic)
 }
 
 
-TEST(Undo_DirtyFlag_CrossesMarkSaved)
+TEST (Undo_DirtyFlag_CrossesMarkSaved)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -312,7 +312,7 @@ TEST(Undo_DirtyFlag_CrossesMarkSaved)
 }
 
 
-TEST(Undo_RoundTrip_Lossless_RandomEdits)
+TEST (Undo_RoundTrip_Lossless_RandomEdits)
 {
 	Buffer b;
 	UndoSystem *u = b.Undo();
@@ -368,7 +368,7 @@ TEST(Undo_RoundTrip_Lossless_RandomEdits)
 
 // Legacy/extended undo tests follow. Keep them available for debugging,
 // but disable them by default to keep the suite focused (~10 tests).
-#if 0
+#if 1
 
 
 TEST (Undo_Branching_RedoPreservedAfterNewEdit)
@@ -713,6 +713,7 @@ TEST (Undo_StructuralInvariants_BranchingAndRoots)
 	validate_undo_tree(*u);
 }
 
+
 TEST (Undo_BranchSelection_ThreeSiblingsAndHeadPersists)
 {
 	Buffer b;
@@ -796,7 +797,7 @@ TEST (Undo_BranchSelection_ThreeSiblingsAndHeadPersists)
 
 
 // Additional legacy tests below are useful, but kept disabled by default.
-#if 0
+#if 1
 
 TEST (Undo_Branching_SwitchBetweenTwoRedoBranches_TextAndCursor)
 {
@@ -1196,4 +1197,167 @@ TEST (Undo_Command_RedoCountSelectsBranch)
 	validate_undo_tree(*u);
 }
 
+
+TEST (Undo_InsertRow_UndoDeletesRow)
+{
+	Buffer b;
+	UndoSystem *u = b.Undo();
+	ASSERT_TRUE(u != nullptr);
+
+	// Seed two lines so insert_row has proper newline context.
+	b.insert_text(0, 0, std::string_view("first\nlast"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+
+	// Insert a row at position 1 (between first and last), then record it.
+	b.insert_row(1, std::string_view("second"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 3);
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("second"));
+
+	b.SetCursor(0, 1);
+	u->Begin(UndoType::InsertRow);
+	u->Append(std::string_view("second"));
+	u->commit();
+
+	// Undo should remove the inserted row.
+	u->undo();
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+	ASSERT_EQ(std::string(b.Rows()[0]), std::string("first"));
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("last"));
+
+	// Redo should re-insert it.
+	u->redo();
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 3);
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("second"));
+
+	validate_undo_tree(*u);
+}
+
+
+TEST (Undo_DeleteRow_UndoRestoresRow)
+{
+	Buffer b;
+	UndoSystem *u = b.Undo();
+	ASSERT_TRUE(u != nullptr);
+
+	b.insert_text(0, 0, std::string_view("alpha\nbeta\ngamma"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 3);
+
+	// Record a DeleteRow for row 1 ("beta").
+	b.SetCursor(0, 1);
+	u->Begin(UndoType::DeleteRow);
+	u->Append(static_cast<std::string>(b.Rows()[1]));
+	u->commit();
+	b.delete_row(1);
+
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+	ASSERT_EQ(std::string(b.Rows()[0]), std::string("alpha"));
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("gamma"));
+
+	// Undo should restore "beta" at row 1.
+	u->undo();
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 3);
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("beta"));
+
+	// Redo should delete it again.
+	u->redo();
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("gamma"));
+
+	validate_undo_tree(*u);
+}
+
+
+TEST (Undo_InsertRow_IsStandalone)
+{
+	Buffer b;
+	UndoSystem *u = b.Undo();
+	ASSERT_TRUE(u != nullptr);
+
+	// Seed with two lines so InsertRow has proper newline context.
+	b.insert_text(0, 0, std::string_view("x\nend"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+
+	// Start a pending insert on row 0.
+	b.SetCursor(1, 0);
+	u->Begin(UndoType::Insert);
+	b.insert_text(0, 1, std::string_view("y"));
+	u->Append('y');
+	b.SetCursor(2, 0);
+
+	// InsertRow should seal the pending "y" and become its own step.
+	b.insert_row(1, std::string_view("row2"));
+	b.SetCursor(0, 1);
+	u->Begin(UndoType::InsertRow);
+	u->Append(std::string_view("row2"));
+	u->commit();
+
+	ASSERT_EQ(std::string(b.Rows()[0]), std::string("xy"));
+	ASSERT_EQ(std::string(b.Rows()[1]), std::string("row2"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 3);
+
+	// Undo InsertRow only.
+	u->undo();
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 2);
+	ASSERT_EQ(std::string(b.Rows()[0]), std::string("xy"));
+
+	// Undo the insert "y".
+	u->undo();
+	ASSERT_EQ(std::string(b.Rows()[0]), std::string("x"));
+
+	validate_undo_tree(*u);
+}
+
+
+TEST (Undo_GroupedDeleteAndInsertRows_UndoesAsUnit)
+{
+	Buffer b;
+	UndoSystem *u = b.Undo();
+	ASSERT_TRUE(u != nullptr);
+
+	// Seed three lines (with trailing newline so delete_row/insert_row work cleanly).
+	b.insert_text(0, 0, std::string_view("aaa\nbbb\nccc\n"));
+	ASSERT_EQ(b.Rows().size(), (std::size_t) 4); // 3 content + 1 empty trailing
+	const std::string original = b.AsString();
+
+	// Group: delete content rows then insert replacements (simulates reflow).
+	(void) u->BeginGroup();
+
+	// Delete rows 2,1,0 in reverse order (like reflow does).
+	for (int i = 2; i >= 0; --i) {
+		b.SetCursor(0, static_cast<std::size_t>(i));
+		u->Begin(UndoType::DeleteRow);
+		u->Append(static_cast<std::string>(b.Rows()[static_cast<std::size_t>(i)]));
+		u->commit();
+		b.delete_row(i);
+	}
+
+	// Insert replacement rows.
+	b.insert_row(0, std::string_view("aaa bbb"));
+	b.SetCursor(0, 0);
+	u->Begin(UndoType::InsertRow);
+	u->Append(std::string_view("aaa bbb"));
+	u->commit();
+
+	b.insert_row(1, std::string_view("ccc"));
+	b.SetCursor(0, 1);
+	u->Begin(UndoType::InsertRow);
+	u->Append(std::string_view("ccc"));
+	u->commit();
+
+	u->EndGroup();
+
+	const std::string reflowed = b.AsString();
+
+	// Single undo should restore original content.
+	u->undo();
+	ASSERT_EQ(b.AsString(), original);
+
+	// Redo should restore the reflowed state.
+	u->redo();
+	ASSERT_EQ(b.AsString(), reflowed);
+
+	validate_undo_tree(*u);
+}
+
+
 #endif // legacy tests

themes/Leuchtturm.h

@@ -0,0 +1,204 @@
+// themes/Leuchtturm.h — Fountain pen on cream paper, brass and leather (header-only)
+// Inspired by Kaweco Brass/Bronze Sport pens on Leuchtturm1917 notebook paper.
+// Light: warm cream paper with blue-black fountain pen ink.
+// Dark: leather case and patinated metal.
+#pragma once
+#include "ThemeHelpers.h"
+
+static inline void
+ApplyLeuchtturmLightTheme()
+{
+	// Notebook paper and fountain pen ink
+	const ImVec4 paper  = RGBA(0xF2ECDF); // Leuchtturm cream paper
+	const ImVec4 bg1    = RGBA(0xE8E2D5); // slightly darker cream
+	const ImVec4 bg2    = RGBA(0xDDD7CA); // UI elements
+	const ImVec4 bg3    = RGBA(0xD1CBBD); // hover/active
+	const ImVec4 ink    = RGBA(0x040720); // blue-black fountain pen ink
+	const ImVec4 dim    = RGBA(0x7A756A); // faded text (like printed headers)
+	const ImVec4 border = RGBA(0xCCC6B4); // faint ruled lines
+
+	// Metal accents from the pens
+	const ImVec4 brass = RGBA(0x6B5E2A); // dark patinated brass
+	const ImVec4 brown = RGBA(0x5C3D28); // leather/bronze
+
+	ImGuiStyle &style      = ImGui::GetStyle();
+	style.WindowPadding    = ImVec2(8.0f, 8.0f);
+	style.FramePadding     = ImVec2(6.0f, 4.0f);
+	style.CellPadding      = ImVec2(6.0f, 4.0f);
+	style.ItemSpacing      = ImVec2(6.0f, 6.0f);
+	style.ItemInnerSpacing = ImVec2(6.0f, 4.0f);
+	style.ScrollbarSize    = 12.0f;
+	style.GrabMinSize      = 10.0f;
+	style.WindowRounding   = 0.0f;
+	style.FrameRounding    = 0.0f;
+	style.PopupRounding    = 0.0f;
+	style.GrabRounding     = 0.0f;
+	style.TabRounding      = 0.0f;
+	style.WindowBorderSize = 1.0f;
+	style.FrameBorderSize  = 0.0f;
+
+	ImVec4 *colors                = style.Colors;
+	colors[ImGuiCol_Text]         = ink;
+	colors[ImGuiCol_TextDisabled] = dim;
+	colors[ImGuiCol_WindowBg]     = paper;
+	colors[ImGuiCol_ChildBg]      = paper;
+	colors[ImGuiCol_PopupBg]      = ImVec4(bg1.x, bg1.y, bg1.z, 0.98f);
+	colors[ImGuiCol_Border]       = border;
+	colors[ImGuiCol_BorderShadow] = RGBA(0x000000, 0.0f);
+
+	colors[ImGuiCol_FrameBg]        = bg2;
+	colors[ImGuiCol_FrameBgHovered] = bg3;
+	colors[ImGuiCol_FrameBgActive]  = bg1;
+
+	colors[ImGuiCol_TitleBg]          = bg1;
+	colors[ImGuiCol_TitleBgActive]    = bg2;
+	colors[ImGuiCol_TitleBgCollapsed] = bg1;
+
+	colors[ImGuiCol_MenuBarBg]            = bg1;
+	colors[ImGuiCol_ScrollbarBg]          = paper;
+	colors[ImGuiCol_ScrollbarGrab]        = bg3;
+	colors[ImGuiCol_ScrollbarGrabHovered] = bg2;
+	colors[ImGuiCol_ScrollbarGrabActive]  = border;
+
+	colors[ImGuiCol_CheckMark]        = ink;
+	colors[ImGuiCol_SliderGrab]       = ink;
+	colors[ImGuiCol_SliderGrabActive] = brass;
+
+	colors[ImGuiCol_Button]        = bg2;
+	colors[ImGuiCol_ButtonHovered] = bg3;
+	colors[ImGuiCol_ButtonActive]  = bg1;
+
+	colors[ImGuiCol_Header]        = bg2;
+	colors[ImGuiCol_HeaderHovered] = bg3;
+	colors[ImGuiCol_HeaderActive]  = bg3;
+
+	colors[ImGuiCol_Separator]        = border;
+	colors[ImGuiCol_SeparatorHovered] = bg3;
+	colors[ImGuiCol_SeparatorActive]  = brass;
+
+	colors[ImGuiCol_ResizeGrip]        = ImVec4(ink.x, ink.y, ink.z, 0.10f);
+	colors[ImGuiCol_ResizeGripHovered] = ImVec4(brass.x, brass.y, brass.z, 0.50f);
+	colors[ImGuiCol_ResizeGripActive]  = brass;
+
+	colors[ImGuiCol_Tab]                = bg2;
+	colors[ImGuiCol_TabHovered]         = bg1;
+	colors[ImGuiCol_TabActive]          = bg3;
+	colors[ImGuiCol_TabUnfocused]       = bg2;
+	colors[ImGuiCol_TabUnfocusedActive] = bg3;
+
+	colors[ImGuiCol_TableHeaderBg]     = bg2;
+	colors[ImGuiCol_TableBorderStrong] = border;
+	colors[ImGuiCol_TableBorderLight]  = ImVec4(border.x, border.y, border.z, 0.5f);
+	colors[ImGuiCol_TableRowBg]        = ImVec4(bg1.x, bg1.y, bg1.z, 0.0f);
+	colors[ImGuiCol_TableRowBgAlt]     = ImVec4(bg1.x, bg1.y, bg1.z, 0.30f);
+
+	colors[ImGuiCol_TextSelectedBg]        = ImVec4(brass.x, brass.y, brass.z, 0.18f);
+	colors[ImGuiCol_DragDropTarget]        = brass;
+	colors[ImGuiCol_NavHighlight]          = brass;
+	colors[ImGuiCol_NavWindowingHighlight] = ImVec4(ink.x, ink.y, ink.z, 0.70f);
+	colors[ImGuiCol_NavWindowingDimBg]     = ImVec4(0.0f, 0.0f, 0.0f, 0.15f);
+	colors[ImGuiCol_ModalWindowDimBg]      = ImVec4(0.0f, 0.0f, 0.0f, 0.15f);
+	colors[ImGuiCol_PlotLines]             = brown;
+	colors[ImGuiCol_PlotLinesHovered]      = brass;
+	colors[ImGuiCol_PlotHistogram]         = brown;
+	colors[ImGuiCol_PlotHistogramHovered]  = brass;
+}
+
+
+// Dark variant — leather pen case with warm metal and cream accents
+static inline void
+ApplyLeuchtturmDarkTheme()
+{
+	const ImVec4 bg0    = RGBA(0x1C1610); // dark leather
+	const ImVec4 bg1    = RGBA(0x251E16); // slightly lighter
+	const ImVec4 bg2    = RGBA(0x30281E); // UI elements
+	const ImVec4 bg3    = RGBA(0x3E3428); // hover/active
+	const ImVec4 ink    = RGBA(0xE5DDD0); // warm cream text
+	const ImVec4 dim    = RGBA(0x978E7C); // secondary text
+	const ImVec4 border = RGBA(0x4A3E30); // subtle borders
+
+	const ImVec4 brass = RGBA(0xB8A060); // polished brass
+	const ImVec4 brown = RGBA(0x8B6848); // bronze pen
+
+	ImGuiStyle &style      = ImGui::GetStyle();
+	style.WindowPadding    = ImVec2(8.0f, 8.0f);
+	style.FramePadding     = ImVec2(6.0f, 4.0f);
+	style.CellPadding      = ImVec2(6.0f, 4.0f);
+	style.ItemSpacing      = ImVec2(6.0f, 6.0f);
+	style.ItemInnerSpacing = ImVec2(6.0f, 4.0f);
+	style.ScrollbarSize    = 12.0f;
+	style.GrabMinSize      = 10.0f;
+	style.WindowRounding   = 0.0f;
+	style.FrameRounding    = 0.0f;
+	style.PopupRounding    = 0.0f;
+	style.GrabRounding     = 0.0f;
+	style.TabRounding      = 0.0f;
+	style.WindowBorderSize = 1.0f;
+	style.FrameBorderSize  = 0.0f;
+
+	ImVec4 *colors                = style.Colors;
+	colors[ImGuiCol_Text]         = ink;
+	colors[ImGuiCol_TextDisabled] = dim;
+	colors[ImGuiCol_WindowBg]     = bg0;
+	colors[ImGuiCol_ChildBg]      = bg0;
+	colors[ImGuiCol_PopupBg]      = ImVec4(bg1.x, bg1.y, bg1.z, 0.98f);
+	colors[ImGuiCol_Border]       = border;
+	colors[ImGuiCol_BorderShadow] = RGBA(0x000000, 0.0f);
+
+	colors[ImGuiCol_FrameBg]        = bg2;
+	colors[ImGuiCol_FrameBgHovered] = bg3;
+	colors[ImGuiCol_FrameBgActive]  = bg1;
+
+	colors[ImGuiCol_TitleBg]          = bg1;
+	colors[ImGuiCol_TitleBgActive]    = bg2;
+	colors[ImGuiCol_TitleBgCollapsed] = bg1;
+
+	colors[ImGuiCol_MenuBarBg]            = bg1;
+	colors[ImGuiCol_ScrollbarBg]          = bg0;
+	colors[ImGuiCol_ScrollbarGrab]        = bg3;
+	colors[ImGuiCol_ScrollbarGrabHovered] = border;
+	colors[ImGuiCol_ScrollbarGrabActive]  = dim;
+
+	colors[ImGuiCol_CheckMark]        = brass;
+	colors[ImGuiCol_SliderGrab]       = brass;
+	colors[ImGuiCol_SliderGrabActive] = brown;
+
+	colors[ImGuiCol_Button]        = bg2;
+	colors[ImGuiCol_ButtonHovered] = bg3;
+	colors[ImGuiCol_ButtonActive]  = bg1;
+
+	colors[ImGuiCol_Header]        = bg2;
+	colors[ImGuiCol_HeaderHovered] = bg3;
+	colors[ImGuiCol_HeaderActive]  = bg3;
+
+	colors[ImGuiCol_Separator]        = border;
+	colors[ImGuiCol_SeparatorHovered] = bg3;
+	colors[ImGuiCol_SeparatorActive]  = brass;
+
+	colors[ImGuiCol_ResizeGrip]        = ImVec4(ink.x, ink.y, ink.z, 0.10f);
+	colors[ImGuiCol_ResizeGripHovered] = ImVec4(brass.x, brass.y, brass.z, 0.50f);
+	colors[ImGuiCol_ResizeGripActive]  = brass;
+
+	colors[ImGuiCol_Tab]                = bg2;
+	colors[ImGuiCol_TabHovered]         = bg1;
+	colors[ImGuiCol_TabActive]          = bg3;
+	colors[ImGuiCol_TabUnfocused]       = bg2;
+	colors[ImGuiCol_TabUnfocusedActive] = bg3;
+
+	colors[ImGuiCol_TableHeaderBg]     = bg2;
+	colors[ImGuiCol_TableBorderStrong] = border;
+	colors[ImGuiCol_TableBorderLight]  = ImVec4(border.x, border.y, border.z, 0.5f);
+	colors[ImGuiCol_TableRowBg]        = ImVec4(bg1.x, bg1.y, bg1.z, 0.0f);
+	colors[ImGuiCol_TableRowBgAlt]     = ImVec4(bg1.x, bg1.y, bg1.z, 0.30f);
+
+	colors[ImGuiCol_TextSelectedBg]        = ImVec4(brass.x, brass.y, brass.z, 0.22f);
+	colors[ImGuiCol_DragDropTarget]        = brass;
+	colors[ImGuiCol_NavHighlight]          = brass;
+	colors[ImGuiCol_NavWindowingHighlight] = ImVec4(ink.x, ink.y, ink.z, 0.70f);
+	colors[ImGuiCol_NavWindowingDimBg]     = ImVec4(0.0f, 0.0f, 0.0f, 0.35f);
+	colors[ImGuiCol_ModalWindowDimBg]      = ImVec4(0.0f, 0.0f, 0.0f, 0.35f);
+	colors[ImGuiCol_PlotLines]             = brass;
+	colors[ImGuiCol_PlotLinesHovered]      = brown;
+	colors[ImGuiCol_PlotHistogram]         = brass;
+	colors[ImGuiCol_PlotHistogramHovered]  = brown;
+}

themes/Tufte.h

@@ -0,0 +1,203 @@
+// themes/Tufte.h — Edward Tufte inspired ImGui theme (header-only)
+// Warm cream paper, dark ink, minimal chrome, restrained accent colors.
+#pragma once
+#include "ThemeHelpers.h"
+
+// Light variant (primary — Tufte's books are fundamentally light)
+static inline void
+ApplyTufteLightTheme()
+{
+	// Tufte palette: warm cream paper with near-black ink
+	const ImVec4 paper  = RGBA(0xFFFFF8); // Tufte's signature warm white
+	const ImVec4 bg1    = RGBA(0xF4F0E8); // slightly darker cream
+	const ImVec4 bg2    = RGBA(0xEAE6DE); // UI elements
+	const ImVec4 bg3    = RGBA(0xDDD9D1); // hover/active
+	const ImVec4 ink    = RGBA(0x111111); // near-black text
+	const ImVec4 dim    = RGBA(0x6B6B6B); // disabled/secondary text
+	const ImVec4 border = RGBA(0xD0CCC4); // subtle borders
+
+	// Tufte uses color sparingly: muted red for emphasis, navy for links
+	const ImVec4 red  = RGBA(0xA00000); // restrained dark red
+	const ImVec4 blue = RGBA(0x1F3F6F); // dark navy
+
+	ImGuiStyle &style      = ImGui::GetStyle();
+	style.WindowPadding    = ImVec2(8.0f, 8.0f);
+	style.FramePadding     = ImVec2(6.0f, 4.0f);
+	style.CellPadding      = ImVec2(6.0f, 4.0f);
+	style.ItemSpacing      = ImVec2(6.0f, 6.0f);
+	style.ItemInnerSpacing = ImVec2(6.0f, 4.0f);
+	style.ScrollbarSize    = 12.0f;
+	style.GrabMinSize      = 10.0f;
+	style.WindowRounding   = 0.0f; // sharp edges — typographic, not app-like
+	style.FrameRounding    = 0.0f;
+	style.PopupRounding    = 0.0f;
+	style.GrabRounding     = 0.0f;
+	style.TabRounding      = 0.0f;
+	style.WindowBorderSize = 1.0f;
+	style.FrameBorderSize  = 0.0f; // minimal frame borders
+
+	ImVec4 *colors                = style.Colors;
+	colors[ImGuiCol_Text]         = ink;
+	colors[ImGuiCol_TextDisabled] = dim;
+	colors[ImGuiCol_WindowBg]     = paper;
+	colors[ImGuiCol_ChildBg]      = paper;
+	colors[ImGuiCol_PopupBg]      = ImVec4(bg1.x, bg1.y, bg1.z, 0.98f);
+	colors[ImGuiCol_Border]       = border;
+	colors[ImGuiCol_BorderShadow] = RGBA(0x000000, 0.0f);
+
+	colors[ImGuiCol_FrameBg]        = bg2;
+	colors[ImGuiCol_FrameBgHovered] = bg3;
+	colors[ImGuiCol_FrameBgActive]  = bg1;
+
+	colors[ImGuiCol_TitleBg]          = bg1;
+	colors[ImGuiCol_TitleBgActive]    = bg2;
+	colors[ImGuiCol_TitleBgCollapsed] = bg1;
+
+	colors[ImGuiCol_MenuBarBg]            = bg1;
+	colors[ImGuiCol_ScrollbarBg]          = paper;
+	colors[ImGuiCol_ScrollbarGrab]        = bg3;
+	colors[ImGuiCol_ScrollbarGrabHovered] = bg2;
+	colors[ImGuiCol_ScrollbarGrabActive]  = border;
+
+	colors[ImGuiCol_CheckMark]        = ink;
+	colors[ImGuiCol_SliderGrab]       = ink;
+	colors[ImGuiCol_SliderGrabActive] = blue;
+
+	colors[ImGuiCol_Button]        = bg2;
+	colors[ImGuiCol_ButtonHovered] = bg3;
+	colors[ImGuiCol_ButtonActive]  = bg1;
+
+	colors[ImGuiCol_Header]        = bg2;
+	colors[ImGuiCol_HeaderHovered] = bg3;
+	colors[ImGuiCol_HeaderActive]  = bg3;
+
+	colors[ImGuiCol_Separator]        = border;
+	colors[ImGuiCol_SeparatorHovered] = bg3;
+	colors[ImGuiCol_SeparatorActive]  = red;
+
+	colors[ImGuiCol_ResizeGrip]        = ImVec4(ink.x, ink.y, ink.z, 0.10f);
+	colors[ImGuiCol_ResizeGripHovered] = ImVec4(red.x, red.y, red.z, 0.50f);
+	colors[ImGuiCol_ResizeGripActive]  = red;
+
+	colors[ImGuiCol_Tab]                = bg2;
+	colors[ImGuiCol_TabHovered]         = bg1;
+	colors[ImGuiCol_TabActive]          = bg3;
+	colors[ImGuiCol_TabUnfocused]       = bg2;
+	colors[ImGuiCol_TabUnfocusedActive] = bg3;
+
+	colors[ImGuiCol_TableHeaderBg]     = bg2;
+	colors[ImGuiCol_TableBorderStrong] = border;
+	colors[ImGuiCol_TableBorderLight]  = ImVec4(border.x, border.y, border.z, 0.5f);
+	colors[ImGuiCol_TableRowBg]        = ImVec4(bg1.x, bg1.y, bg1.z, 0.0f);
+	colors[ImGuiCol_TableRowBgAlt]     = ImVec4(bg1.x, bg1.y, bg1.z, 0.30f);
+
+	colors[ImGuiCol_TextSelectedBg]        = ImVec4(red.x, red.y, red.z, 0.15f);
+	colors[ImGuiCol_DragDropTarget]        = red;
+	colors[ImGuiCol_NavHighlight]          = red;
+	colors[ImGuiCol_NavWindowingHighlight] = ImVec4(ink.x, ink.y, ink.z, 0.70f);
+	colors[ImGuiCol_NavWindowingDimBg]     = ImVec4(0.0f, 0.0f, 0.0f, 0.15f);
+	colors[ImGuiCol_ModalWindowDimBg]      = ImVec4(0.0f, 0.0f, 0.0f, 0.15f);
+	colors[ImGuiCol_PlotLines]             = blue;
+	colors[ImGuiCol_PlotLinesHovered]      = red;
+	colors[ImGuiCol_PlotHistogram]         = blue;
+	colors[ImGuiCol_PlotHistogramHovered]  = red;
+}
+
+
+// Dark variant — warm charcoal with cream ink, same restrained accents
+static inline void
+ApplyTufteDarkTheme()
+{
+	const ImVec4 bg0    = RGBA(0x1C1B19); // warm near-black
+	const ImVec4 bg1    = RGBA(0x252420); // slightly lighter
+	const ImVec4 bg2    = RGBA(0x302F2A); // UI elements
+	const ImVec4 bg3    = RGBA(0x3D3C36); // hover/active
+	const ImVec4 ink    = RGBA(0xEAE6DE); // cream text (inverted paper)
+	const ImVec4 dim    = RGBA(0x9A9690); // disabled text
+	const ImVec4 border = RGBA(0x4A4840); // subtle borders
+
+	const ImVec4 red  = RGBA(0xD06060); // warmer red for dark bg
+	const ImVec4 blue = RGBA(0x7098C0); // lighter navy for dark bg
+
+	ImGuiStyle &style      = ImGui::GetStyle();
+	style.WindowPadding    = ImVec2(8.0f, 8.0f);
+	style.FramePadding     = ImVec2(6.0f, 4.0f);
+	style.CellPadding      = ImVec2(6.0f, 4.0f);
+	style.ItemSpacing      = ImVec2(6.0f, 6.0f);
+	style.ItemInnerSpacing = ImVec2(6.0f, 4.0f);
+	style.ScrollbarSize    = 12.0f;
+	style.GrabMinSize      = 10.0f;
+	style.WindowRounding   = 0.0f;
+	style.FrameRounding    = 0.0f;
+	style.PopupRounding    = 0.0f;
+	style.GrabRounding     = 0.0f;
+	style.TabRounding      = 0.0f;
+	style.WindowBorderSize = 1.0f;
+	style.FrameBorderSize  = 0.0f;
+
+	ImVec4 *colors                = style.Colors;
+	colors[ImGuiCol_Text]         = ink;
+	colors[ImGuiCol_TextDisabled] = dim;
+	colors[ImGuiCol_WindowBg]     = bg0;
+	colors[ImGuiCol_ChildBg]      = bg0;
+	colors[ImGuiCol_PopupBg]      = ImVec4(bg1.x, bg1.y, bg1.z, 0.98f);
+	colors[ImGuiCol_Border]       = border;
+	colors[ImGuiCol_BorderShadow] = RGBA(0x000000, 0.0f);
+
+	colors[ImGuiCol_FrameBg]        = bg2;
+	colors[ImGuiCol_FrameBgHovered] = bg3;
+	colors[ImGuiCol_FrameBgActive]  = bg1;
+
+	colors[ImGuiCol_TitleBg]          = bg1;
+	colors[ImGuiCol_TitleBgActive]    = bg2;
+	colors[ImGuiCol_TitleBgCollapsed] = bg1;
+
+	colors[ImGuiCol_MenuBarBg]            = bg1;
+	colors[ImGuiCol_ScrollbarBg]          = bg0;
+	colors[ImGuiCol_ScrollbarGrab]        = bg3;
+	colors[ImGuiCol_ScrollbarGrabHovered] = border;
+	colors[ImGuiCol_ScrollbarGrabActive]  = dim;
+
+	colors[ImGuiCol_CheckMark]        = ink;
+	colors[ImGuiCol_SliderGrab]       = ink;
+	colors[ImGuiCol_SliderGrabActive] = blue;
+
+	colors[ImGuiCol_Button]        = bg2;
+	colors[ImGuiCol_ButtonHovered] = bg3;
+	colors[ImGuiCol_ButtonActive]  = bg1;
+
+	colors[ImGuiCol_Header]        = bg2;
+	colors[ImGuiCol_HeaderHovered] = bg3;
+	colors[ImGuiCol_HeaderActive]  = bg3;
+
+	colors[ImGuiCol_Separator]        = border;
+	colors[ImGuiCol_SeparatorHovered] = bg3;
+	colors[ImGuiCol_SeparatorActive]  = red;
+
+	colors[ImGuiCol_ResizeGrip]        = ImVec4(ink.x, ink.y, ink.z, 0.10f);
+	colors[ImGuiCol_ResizeGripHovered] = ImVec4(red.x, red.y, red.z, 0.50f);
+	colors[ImGuiCol_ResizeGripActive]  = red;
+
+	colors[ImGuiCol_Tab]                = bg2;
+	colors[ImGuiCol_TabHovered]         = bg1;
+	colors[ImGuiCol_TabActive]          = bg3;
+	colors[ImGuiCol_TabUnfocused]       = bg2;
+	colors[ImGuiCol_TabUnfocusedActive] = bg3;
+
+	colors[ImGuiCol_TableHeaderBg]     = bg2;
+	colors[ImGuiCol_TableBorderStrong] = border;
+	colors[ImGuiCol_TableBorderLight]  = ImVec4(border.x, border.y, border.z, 0.5f);
+	colors[ImGuiCol_TableRowBg]        = ImVec4(bg1.x, bg1.y, bg1.z, 0.0f);
+	colors[ImGuiCol_TableRowBgAlt]     = ImVec4(bg1.x, bg1.y, bg1.z, 0.30f);
+
+	colors[ImGuiCol_TextSelectedBg]        = ImVec4(red.x, red.y, red.z, 0.20f);
+	colors[ImGuiCol_DragDropTarget]        = red;
+	colors[ImGuiCol_NavHighlight]          = red;
+	colors[ImGuiCol_NavWindowingHighlight] = ImVec4(ink.x, ink.y, ink.z, 0.70f);
+	colors[ImGuiCol_NavWindowingDimBg]     = ImVec4(0.0f, 0.0f, 0.0f, 0.35f);
+	colors[ImGuiCol_ModalWindowDimBg]      = ImVec4(0.0f, 0.0f, 0.0f, 0.35f);
+	colors[ImGuiCol_PlotLines]             = blue;
+	colors[ImGuiCol_PlotLinesHovered]      = red;
+	colors[ImGuiCol_PlotHistogram]         = blue;
+	colors[ImGuiCol_PlotHistogramHovered]  = red;
+}