Add proportional fonts, edit modes, and TOML config

- Add three proportional serif fonts: Crimson Pro, ET Book, Spectral
- Fix text rendering for variable-width fonts: selection, cursor,
  mouse click mapping, search highlights, and syntax-colored text
  now use pixel-accurate measurement via ImGui::CalcTextSize()
- Add per-buffer edit mode (code/writing) with auto-detection from
  file extension (.txt, .md, .rst, .org, .tex default to writing)
- Add C-k m keybinding and :mode command to toggle edit modes
- Switch config format from INI to TOML (kge.toml), with legacy
  INI fallback; vendor toml++ v3.4.0
- New config keys: font.code and font.writing for per-mode defaults
- Add font tab completion for ImGui builds
- Add tab completion for :mode command
- Update help text, themes.md, and add CONFIG.md
- Bump version to 1.10.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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 +507,27 @@ public:
 	}
 
 
+	// Edit mode (code vs writing)
+	[[nodiscard]] EditMode GetEditMode() const
+	{
+		return edit_mode_;
+	}
+
+
+	void SetEditMode(EditMode m)
+	{
+		edit_mode_ = m;
+	}
+
+
+	void ToggleEditMode()
+	{
+		edit_mode_ = (edit_mode_ == EditMode::Code)
+			             ? EditMode::Writing
+			             : EditMode::Code;
+	}
+
+
 	void SetSyntaxEnabled(bool on)
 	{
 		syntax_enabled_ = on;
@@ -614,6 +658,9 @@ private:
 	std::unique_ptr<struct UndoTree> undo_tree_;
 	std::unique_ptr<UndoSystem> undo_sys_;
 
+	// Edit mode (code vs writing)
+	EditMode edit_mode_ = EditMode::Code;
+
 	// Syntax/highlighting state
 	std::uint64_t version_ = 0; // increment on edits
 	bool syntax_enabled_   = true;

CMakeLists.txt

@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 
 set(CMAKE_CXX_STANDARD 20)
-set(KTE_VERSION "1.9.1")
+set(KTE_VERSION "1.10.0")
 
 # Default to terminal-only build to avoid SDL/OpenGL dependency by default.
 # Enable with -DBUILD_GUI=ON when SDL2/OpenGL/Freetype are available.
@@ -205,6 +205,8 @@ 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
@@ -216,6 +218,7 @@ set(FONT_HEADERS
         fonts/IosevkaExtended.h
         fonts/ShareTech.h
         fonts/SpaceMono.h
+        fonts/Spectral.h
         fonts/Syne.h
         fonts/Triplicate.h
         fonts/Unispace.h

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

@@ -1335,6 +1335,40 @@ 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();
+	}
+
+	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
@@ -1888,15 +1922,15 @@ 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;
@@ -1907,6 +1941,13 @@ 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) {
@@ -1927,9 +1968,19 @@ 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());
@@ -5025,6 +5076,11 @@ InstallDefaultCommands()
 		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

@@ -117,6 +117,8 @@ enum class CommandId {
 	FontZoomIn,
 	FontZoomOut,
 	FontZoomReset,
+	// Edit mode (code/writing)
+	ToggleEditMode,
 };
 
 

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)
@@ -19,32 +39,104 @@ 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]
+	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;
+		if (auto v = (*sec)["writing"].value<std::string>())
+			writing_font = *v;
+	}
+
+	// [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;
+	}
+
+	return true;
+}
+
+
+bool
+GUIConfig::LoadFromINI(const std::string &path)
 {
 	std::ifstream in(path);
 	if (!in.good())
@@ -104,6 +196,10 @@ GUIConfig::LoadFromFile(const std::string &path)
 			}
 		} else if (key == "font") {
 			font = val;
+		} else if (key == "code_font") {
+			code_font = val;
+		} else if (key == "writing_font") {
+			writing_font = val;
 		} else if (key == "theme") {
 			theme = val;
 		} else if (key == "background" || key == "bg") {

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);
 };

HelpText.cc

@@ -41,6 +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"
@@ -82,12 +83,24 @@ HelpText::Text()
 		"\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 config file options:\n"
+		"GUI commands (command prompt):\n"
-		"  font_size=NUM        Set font size in pixels (default: 16; e.g., font_size=18)\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"

ImGuiFrontend.cc

@@ -38,6 +38,11 @@ apply_syntax_to_buffer(Buffer *b, const GUIConfig &cfg)
 {
 	if (!b)
 		return;
+
+	// Auto-detect edit mode from file extension
+	if (!b->Filename().empty())
+		b->SetEditMode(DetectEditMode(b->Filename()));
+
 	if (cfg.syntax) {
 		b->SetSyntaxEnabled(true);
 		b->EnsureHighlighter();
@@ -518,6 +523,9 @@ GUIFrontend::Step(Editor &ed, bool &running)
 		// Allow deferred opens
 		wed.ProcessPendingOpens();
 
+		// Ensure newly opened buffers get syntax + edit mode detection
+		apply_syntax_to_buffer(wed.CurrentBuffer(), config_);
+
 		// Drain input queue
 		for (;;) {
 			MappedInput mi;
@@ -557,6 +565,25 @@ GUIFrontend::Step(Editor &ed, bool &running)
 			running = false;
 		}
 
+		// Switch font based on current buffer's edit mode
+		{
+			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.LoadFont(expected, sz);
+					ImGui_ImplOpenGL3_DestroyFontsTexture();
+					ImGui_ImplOpenGL3_CreateFontsTexture();
+				}
+			}
+		}
+
 		// Draw
 		ws.renderer.Draw(wed);
 

ImGuiRenderer.cc

@@ -175,29 +175,54 @@ 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};
@@ -244,11 +269,37 @@ ImGuiRenderer::Draw(Editor &ed)
 			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 pixel x offset
+			// relative to the visible line start, using actual text measurement
+			// so proportional fonts render correctly.
+			auto rx_to_px = [&](std::size_t rx_col) -> float {
+				if (rx_col <= coloffs_now)
+					return 0.0f;
+				std::size_t start = coloffs_now;
+				std::size_t end   = std::min(expanded.size(), rx_col);
+				if (start >= expanded.size() || end <= start)
+					return 0.0f;
+				return ImGui::CalcTextSize(expanded.c_str() + start,
+				                           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;
@@ -303,10 +354,8 @@ ImGuiRenderer::Draw(Editor &ed)
 					// Apply horizontal scroll offset
 					if (rx_end <= coloffs_now)
 						continue; // fully left of view
-					std::size_t vx0 = (rx_start > coloffs_now) ? (rx_start - coloffs_now) : 0;
+					ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start), line_pos.y);
-					std::size_t vx1 = rx_end - coloffs_now;
+					ImVec2 p1 = ImVec2(line_pos.x + rx_to_px(rx_end),
-					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;
@@ -344,13 +393,9 @@ ImGuiRenderer::Draw(Editor &ed)
 					std::size_t rx_start = src_to_rx(sx);
 					std::size_t rx_end   = src_to_rx(ex);
 					if (rx_end > coloffs_now) {
-						std::size_t vx0 = (rx_start > coloffs_now)
+						ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start),
-							                  ? (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);
@@ -369,31 +414,14 @@ ImGuiRenderer::Draw(Editor &ed)
 					rx_end = rx_start + 1;
 				}
 				if (rx_end > coloffs_now) {
-					std::size_t vx0 = (rx_start > coloffs_now)
+					ImVec2 p0 = ImVec2(line_pos.x + rx_to_px(rx_start),
-						                  ? (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(
@@ -445,10 +473,9 @@ ImGuiRenderer::Draw(Editor &ed)
 					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
+					// Screen position via actual text measurement
-					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);
@@ -472,28 +499,8 @@ ImGuiRenderer::Draw(Editor &ed)
 
 			// 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
@@ -539,29 +546,40 @@ 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();

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;

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.
 

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

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 )