Fix multi-window architecture and swap file cleanup

Multi-window:
- Per-window ImGui contexts (fixes input, scroll, and rendering isolation)
- Per-instance scroll and mouse state in ImGuiRenderer (no more statics)
- Proper GL context activation during window destruction
- ValidateBufferIndex guards against stale curbuf_ across shared buffers
- Editor methods (CurrentBuffer, SwitchTo, CloseBuffer, etc.) use Buffers()
  accessor to respect shared buffer lists
- New windows open with an untitled buffer
- Scratch buffer reuse works in secondary windows
- CMD-w on macOS closes only the focused window
- Deferred new-window creation to avoid mid-frame ImGui context corruption

Swap file cleanup:
- SaveAs prompt handler now calls ResetJournal
- cmd_save_and_quit now calls ResetJournal
- Editor::Reset detaches all buffers before clearing
- Tests for save-and-quit and editor-reset swap cleanup

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

CMakeLists.txt

@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 
 set(CMAKE_CXX_STANDARD 20)
-set(KTE_VERSION "1.7.0")
+set(KTE_VERSION "1.9.0")
 
 # 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" ON)
 
 # Optionally enable AddressSanitizer (ASan)
 option(ENABLE_ASAN "Enable AddressSanitizer for builds" OFF)
@@ -285,7 +286,7 @@ 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 +327,7 @@ 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 +338,8 @@ 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 +377,7 @@ 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 +420,7 @@ 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 ()
 

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;
@@ -1109,7 +1121,6 @@ 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
 	std::string name = ctx.arg;
@@ -2255,10 +2266,8 @@ 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 +2572,10 @@ 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 +2962,58 @@ 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 +4689,14 @@ 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 +4705,12 @@ 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 +4884,9 @@ 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 +5016,11 @@ 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
+	});
 }
 
 

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 +111,8 @@ 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,
 };
 
 

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

GUITheme.h

@@ -330,6 +330,7 @@ enum class ThemeId {
 	Amber = 10,
 	WeylandYutani = 11,
 	Orbital = 12,
+	Tufte = 13,
 };
 
 // Current theme tracking
@@ -377,6 +378,7 @@ BackgroundModeName()
 #include "themes/WeylandYutani.h"
 #include "themes/Zenburn.h"
 #include "themes/Orbital.h"
+#include "themes/Tufte.h"
 
 
 // Theme abstraction and registry (generalized theme system)
@@ -488,6 +490,28 @@ 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
 	{
@@ -657,7 +681,7 @@ 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, 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>());
@@ -669,6 +693,7 @@ ThemeRegistry()
 		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>());
 	}
@@ -855,10 +880,12 @@ ThemeIndexFromId(const ThemeId id)
 		return 9;
 	case ThemeId::Solarized:
 		return 10;
-	case ThemeId::WeylandYutani:
+	case ThemeId::Tufte:
 		return 11;
-	case ThemeId::Zenburn:
+	case ThemeId::WeylandYutani:
 		return 12;
+	case ThemeId::Zenburn:
+		return 13;
 	}
 	return 0;
 }
@@ -892,8 +919,10 @@ ThemeIdFromIndex(const size_t idx)
 	case 10:
 		return ThemeId::Solarized;
 	case 11:
-		return ThemeId::WeylandYutani;
+		return ThemeId::Tufte;
 	case 12:
+		return ThemeId::WeylandYutani;
+	case 13:
 		return ThemeId::Zenburn;
 	}
 }

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"
@@ -63,6 +64,10 @@ 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 +79,20 @@ 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"
 		"  : theme NAME         Set GUI theme (amber, eink, everforest, gruvbox, kanagawa-paper, lcars, nord, old-book, plan9, solarized, weyland-yutani, zenburn)\n"
 		"  : background MODE    Set background: light | dark (affects eink, gruvbox, old-book, solarized)\n"
+		"\n"
+		"GUI config file options:\n"
+		"  font_size=NUM        Set font size in pixels (default: 16; e.g., font_size=18)\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 +29,143 @@
 
 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;
+	if (cfg.syntax) {
+		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();
+	float ch_w  = ImGui::CalcTextSize("M").x;
+	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 +178,114 @@ 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 +293,90 @@ 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 +384,214 @@ 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
+		// 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 {
+					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.
+		// Draw
-
+		ws.renderer.Draw(wed);
-	// Draw editor UI
-	renderer_.Draw(ed);
 
 		// 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 +605,6 @@ 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 +612,6 @@ 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 +337,18 @@ 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;
+			}
+		}
+
 		// 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)) {
@@ -442,9 +458,11 @@ ImGuiInputHandler::ProcessSDLEvent(const SDL_Event &e)
 		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

@@ -76,19 +76,16 @@ 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) {
+		if (prev_buf_coloffs_ >= 0 && buf_coloffs != prev_buf_coloffs_) {
 			float target_x = static_cast<float>(buf_coloffs) * space_w;
 			float target_y = static_cast<float>(buf_rowoffs) * row_h;
 			ImGui::SetNextWindowScroll(ImVec2(target_x, target_y));
@@ -116,25 +113,22 @@ ImGuiRenderer::Draw(Editor &ed)
 		// 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 (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) {
+			if (prev_scroll_x_ >= 0.0f && scroll_x != prev_scroll_x_ && !forced_scroll) {
 				if (Buffer *mbuf = const_cast<Buffer *>(buf)) {
 					mbuf->SetOffsets(mbuf->Rowoffs(),
 					                 static_cast<std::size_t>(std::max(0L, scroll_left)));
@@ -142,11 +136,11 @@ ImGuiRenderer::Draw(Editor &ed)
 			}
 
 			// Update trackers for next frame
-			prev_scroll_y = scroll_y;
+			prev_scroll_y_ = scroll_y;
-			prev_scroll_x = scroll_x;
+			prev_scroll_x_ = scroll_x;
 		}
-		prev_buf_rowoffs = buf_rowoffs;
+		prev_buf_rowoffs_ = buf_rowoffs;
-		prev_buf_coloffs = buf_coloffs;
+		prev_buf_coloffs_ = buf_coloffs;
 		// Cache current horizontal offset in rendered columns for click handling
 		const std::size_t coloffs_now = buf->Coloffs();
 
@@ -169,7 +163,7 @@ 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
@@ -209,25 +203,41 @@ ImGuiRenderer::Draw(Editor &ed)
 			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) {
 			// Capture the screen position before drawing the line

ImGuiRenderer.h

@@ -11,4 +11,13 @@ 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;
 };

KKeymap.cc

@@ -226,6 +226,10 @@ 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

@@ -48,6 +48,7 @@ stdenv.mkDerivation {
     "-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"
   ];
 
   installPhase = ''

main.cc

@@ -117,6 +117,9 @@ 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

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

@@ -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/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;
+}