WebKitGTK 6.0 / GTK4 Implementation Tracker

Overview

This document tracks the implementation of WebKitGTK 6.0 (GTK4) support for Wails v3 on Linux.

Current goal (post-flip, 2026-05-16): GTK4 + WebKitGTK 6.0 is the default Linux stack for v3.0.0 GA. GTK3 + WebKit2GTK 4.1 is a legacy opt-in via -tags gtk3 for one v3 cycle and is scheduled for removal in v3.1.

Original goal (2026-02-04, superseded by Decision 1.1): Provide GTK4/WebKitGTK 6.0 support as an EXPERIMENTAL opt-in via -tags gtk4, while maintaining GTK3/WebKit2GTK 4.1 as the stable default.

Architecture Decisions

Decision 1.1: GTK4 as Default, GTK3 Opt-In (2026-05-16) — supersedes Decision 1

Context: GTK4 + WebKitGTK 6.0 has matured through the v3 alpha cycle (alpha.74 → alpha.92). For v3.0.0 GA, shipping with the modern stack as default-of-least-resistance — rather than as an experimental opt-in — is required so distros and packagers do not need to learn a Wails-specific build tag to get a working build.

Decision: GTK4 + WebKitGTK 6.0 is the default. GTK3 + WebKit2GTK 4.1 is opt-in via -tags gtk3. The legacy path stays through the v3.0.x line and is removed in v3.1.

Rationale:

• Removes a discovery hurdle for new users on modern distros (Ubuntu 24.04+, Fedora 40+, Arch, NixOS unstable) — go build Just Works
• Aligns with where the broader GTK ecosystem is moving — GTK3 EOL is on the horizon
• Distros still on WebKit2GTK 4.1 (Ubuntu 22.04 LTS, Debian 12, Fedora ≤ 39, RHEL 9.x) get a clearly-named opt-in until those LTSes age out
• The -tags gtk3 escape hatch lets us defer the breaking change of dropping GTK3 entirely to v3.1

Implementation (issue #5459): Build-tag flip + file renames. Files previously named *_linux_gtk4.go become the bare *_linux.go defaults with constraint !gtk3; files previously named *_linux.go become *_linux_gtk3.go with constraint gtk3. The gtk4 build tag is retired in favor of gtk3 as the toggle. Legacy wails3 doctor package-manager polarity inverted (gtk4/webkitgtk-6.0 required, gtk3/webkit2gtk-4.1 optional legacy). doctor-ng already had the correct polarity.

Decision 1: GTK3 as Default, GTK4 Opt-In (2026-02-04) — SUPERSEDED by Decision 1.1

Context: Need to support modern Linux distributions with GTK4 while maintaining stability for existing apps.

Decision: GTK3 remains the stable default (no build tag required). GTK4 is available as experimental via -tags gtk4.

Rationale:

• GTK3/WebKit2GTK 4.1 is battle-tested and widely deployed
• GTK4 support needs more community testing before becoming default
• Allows gradual migration and feedback collection
• Protects existing apps from unexpected breakage

Build Tags (post-Decision 1.1, post-#5463 review fixes):

• Default (no tag): //go:build linux && cgo && !gtk3 && !android && !server
• Legacy GTK3 opt-in: //go:build linux && cgo && gtk3 && !android && !server
• Server mode (-tags server) excludes both paths so no GTK/cgo code is linked.

Decision 2: pkg-config Libraries (2026-01-04)

GTK4/WebKitGTK 6.0:

#cgo linux pkg-config: gtk4 webkitgtk-6.0 libsoup-3.0

GTK3/WebKit2GTK 4.1 (legacy):

#cgo linux pkg-config: gtk+-3.0 webkit2gtk-4.1 libsoup-3.0

Decision 3: Wayland Window Positioning (2026-01-04)

Context: GTK4/Wayland doesn't support arbitrary window positioning - this is a Wayland protocol limitation.

Decision: Window positioning functions (move(), setPosition(), center()) are documented NO-OPs on GTK4/Wayland.

Rationale: This is a fundamental Wayland design decision, not a limitation we can work around. Users need to be aware of this behavioral difference.

Decision 4: Menu System Architecture (2026-01-04)

Context: GTK4 removes GtkMenu/GtkMenuItem in favor of GMenu/GAction.

Decision: Complete rewrite of menu system for GTK4 using GMenu/GAction/GtkPopoverMenuBar.

Status: Stub implementations only. Full implementation pending.

Decision 5: System Tray Compatibility (2026-01-04)

Context: v3's system tray uses D-Bus StatusNotifierItem protocol.

Decision: No changes needed - system tray is already GTK-agnostic.

Implementation Progress

Phase 1: Build Infrastructure ✅ COMPLETE

Commit: a0ca13fdc (2026-01-04)

1.1 Add gtk3 constraint to existing files

Files modified:

• v3/pkg/application/application_linux.go - Added gtk3 constraint
• v3/pkg/application/linux_cgo.go - Added gtk3 constraint
• v3/internal/assetserver/webview/request_linux.go - Added gtk3 constraint
• v3/internal/assetserver/webview/responsewriter_linux.go - Added gtk3 constraint
• v3/internal/assetserver/webview/webkit2.go - Added gtk3 constraint

1.2 Create GTK4 stub files

Files created:

• v3/pkg/application/linux_cgo_gtk4.go (~1000 lines)

  • Main CGO file with GTK4 bindings
  • Implements: window management, clipboard, basic menu stubs
  • Uses gtk4 webkitgtk-6.0 pkg-config

• v3/pkg/application/application_linux_gtk4.go (~250 lines)

  • Application lifecycle management
  • System theme detection via D-Bus
  • NVIDIA DMA-BUF workaround for Wayland

1.3 Create WebKitGTK 6.0 asset server stubs

Files created:

• v3/internal/assetserver/webview/webkit6.go
• v3/internal/assetserver/webview/request_linux_gtk4.go
• v3/internal/assetserver/webview/responsewriter_linux_gtk4.go

Phase 2: Doctor & Capabilities ✅ COMPLETE

Goal: Update wails doctor to check for GTK4 as primary, GTK3 as secondary.

2.1 Package Manager Updates

All 7 package managers updated to check GTK4/WebKitGTK 6.0 as primary, GTK3 as optional/legacy:

• v3/internal/doctor/packagemanager/apt.go ✅
• v3/internal/doctor/packagemanager/dnf.go ✅
• v3/internal/doctor/packagemanager/pacman.go ✅
• v3/internal/doctor/packagemanager/zypper.go ✅
• v3/internal/doctor/packagemanager/emerge.go ✅
• v3/internal/doctor/packagemanager/eopkg.go ✅
• v3/internal/doctor/packagemanager/nixpkgs.go ✅

Package key naming convention (post-#5463 default flip): gtk4, webkitgtk-6.0 (primary/default), gtk3 (legacy), webkit2gtk (legacy) (optional, removed in v3.1)

2.2 Capabilities Detection

Files created/updated:

• v3/internal/capabilities/capabilities.go - Added GTKVersion (int) and WebKitVersion (string) fields
• v3/internal/capabilities/capabilities_linux.go - GTK4 default: GTKVersion: 4, WebKitVersion: "6.0"
• v3/internal/capabilities/capabilities_linux_gtk3.go - GTK3 legacy: GTKVersion: 3, WebKitVersion: "4.1"

TODO (deferred to Phase 3):

• Update v3/internal/doctor/doctor_linux.go - Improve output to show GTK4 vs GTK3 status

Phase 3: Window Management ✅ COMPLETE

3.1 GTK4 Event Controllers

GTK4 replaces direct signal handlers with GtkEventController objects:

• GtkEventControllerFocus for focus in/out events
• GtkGestureClick for button press/release events
• GtkEventControllerKey for keyboard events
• Window signals: close-request, notify::maximized, notify::fullscreened

New C function setupWindowEventControllers() sets up all event controllers.

3.2 Window Drag and Resize

GTK4 uses GdkToplevel API instead of GTK3's gtk_window_begin_move_drag:

• gdk_toplevel_begin_move() for window drag
• gdk_toplevel_begin_resize() for window resize
• Requires gtk_native_get_surface() to get the GdkSurface

3.3 Drag-and-Drop with GtkDropTarget

Complete implementation using GTK4's GtkDropTarget:

• on_drop_enter / on_drop_leave for drag enter/exit events
• on_drop_motion for drag position updates
• on_drop handles file drops via GDK_TYPE_FILE_LIST
• Go callbacks: onDropEnter, onDropLeave, onDropMotion, onDropFiles

3.4 Window State Detection

• isMinimised() uses gdk_toplevel_get_state() with GDK_TOPLEVEL_STATE_MINIMIZED
• isMaximised() uses gtk_window_is_maximized()
• isFullscreen() uses gtk_window_is_fullscreen()

3.5 Size Constraints

GTK4 removed gtk_window_set_geometry_hints(). Now using gtk_widget_set_size_request() for minimum size.

TODO (deferred):

• Test window lifecycle on GTK4 with actual GTK4 libraries

Phase 4: Menu System ✅ COMPLETE

GTK4 completely replaced the menu system. GTK3's GtkMenu/GtkMenuItem are gone.

4.1 GMenu/GAction Architecture

• GMenu - Menu model (data structure, not a widget)
• GMenuItem - Individual menu item in the model
• GSimpleAction - Action that gets triggered when menu item is activated
• GSimpleActionGroup - Container for actions, attached to widgets

4.2 Menu Bar Implementation

• GtkPopoverMenuBar created from GMenu model via create_menu_bar_from_model()
• Action group attached to window with attach_action_group_to_widget()
• Actions use "app.action_name" namespace

4.3 New Files Created

• v3/pkg/application/menu_linux_gtk4.go - GTK4 menu processing
• v3/pkg/application/menuitem_linux_gtk4.go - GTK4 menu item handling

4.4 Build Tag Changes

• menu_linux.go - Added gtk3 tag
• menuitem_linux.go - Added gtk3 tag

4.5 Key Functions

• menuActionActivated() - Callback when GAction is triggered
• menuItemNewWithId() - Creates GMenuItem + associated GSimpleAction
• menuCheckItemNewWithId() - Creates stateful toggle action
• menuRadioItemNewWithId() - Creates radio action
• set_action_enabled() / set_action_state() - Manage action state

TODO (deferred):

• Context menus with GtkPopoverMenu

Phase 5: Asset Server ✅ COMPLETE

WebKitGTK 6.0 uses the same URI scheme handler API as WebKitGTK 4.1. The asset server implementation is identical between GTK3 and GTK4.

5.1 Asset Server Files (already created in Phase 1)

• v3/internal/assetserver/webview/webkit6.go - WebKitGTK 6.0 helpers
• v3/internal/assetserver/webview/request_linux_gtk4.go - Request handling
• v3/internal/assetserver/webview/responsewriter_linux_gtk4.go - Response writing

5.2 Missing Exports Added

The GTK4 CGO file was missing two critical exports that were in the GTK3 file:

• onProcessRequest - Handles URI scheme requests from WebKit
• sendMessageToBackend - Handles JavaScript to Go communication

Both exports were added to linux_cgo_gtk4.go.

5.3 Key Differences from GTK3

TODO (deferred to testing phase):

• Test asset loading on actual GTK4 system
• Verify JavaScript execution works correctly

Phase 6: Docker & Build System ✅ COMPLETE

6.1 Docker Container Updates

Updated both Dockerfile.linux-x86_64 and Dockerfile.linux-arm64 to install:

• GTK3 + WebKit2GTK 4.1 (default build target)
• GTK4 + WebKitGTK 6.0 (for experimental -tags gtk4 builds)

Build scripts now support BUILD_TAGS environment variable:

• Default: Builds with GTK3/WebKit2GTK 4.1
• BUILD_TAGS=gtk4: Builds with GTK4/WebKitGTK 6.0 (experimental)

6.2 Taskfile Targets

New targets added to v3/Taskfile.yaml:

TODO (deferred):

• Update CI/CD workflows to test both GTK versions

Phase 8: Dialog System ✅ COMPLETE

GTK4 completely replaced the dialog APIs. GTK3's GtkFileChooserDialog and gtk_message_dialog_new are deprecated/removed.

8.1 File Dialogs

GTK4 uses GtkFileDialog with async API:

• gtk_file_dialog_open() - Open single file
• gtk_file_dialog_open_multiple() - Open multiple files
• gtk_file_dialog_select_folder() - Select folder
• gtk_file_dialog_select_multiple_folders() - Select multiple folders
• gtk_file_dialog_save() - Save file

Key differences:

• No more gtk_dialog_run() - everything is async with callbacks
• Filters use GListStore of GtkFileFilter objects
• Results delivered via GAsyncResult callbacks
• Custom button text via gtk_file_dialog_set_accept_label()

8.1.1 GTK4 File Dialog Limitations (Portal-based)

GTK4's GtkFileDialog uses xdg-desktop-portal for native file dialogs. This provides better desktop integration but removes some application control:

Why these limitations exist: GTK4's portal-based dialogs delegate UI control to the desktop environment (GNOME, KDE, etc.). This is intentional - the portal provides consistent UX across applications and respects user preferences.

8.2 Message Dialogs

GTK4 uses GtkAlertDialog:

• gtk_alert_dialog_choose() - Show dialog with buttons
• Buttons specified as NULL-terminated string array
• Default and cancel button indices configurable

8.3 Implementation Details

• Request ID tracking for async callback matching
• fileDialogCallback / alertDialogCallback C exports for results
• runChooserDialog() and runQuestionDialog() Go wrappers
• runOpenFileDialog() and runSaveFileDialog() convenience functions

Phase 9: Keyboard Accelerators ✅ COMPLETE

GTK4 uses gtk_application_set_accels_for_action() to bind keyboard shortcuts to GActions.

9.1 Key Components

C Helper Functions (in linux_cgo_gtk4.go):

• set_action_accelerator(app, action_name, accel) - Sets accelerator for a GAction
• build_accelerator_string(key, mods) - Converts key+modifiers to GTK accelerator string

Go Functions (in linux_cgo_gtk4.go):

• namedKeysToGTK - Map of key names to GDK keysym values (e.g., "backspace" → 0xff08)
• parseKeyGTK(key) - Converts Wails key string to GDK keysym
• parseModifiersGTK(modifiers) - Converts Wails modifiers to GdkModifierType
• acceleratorToGTK(accel) - Converts full accelerator to GTK format
• setMenuItemAccelerator(itemId, accel) - Sets accelerator for a menu item

Integration (in menuitem_linux_gtk4.go):

• setAccelerator() method on linuxMenuItem calls setMenuItemAccelerator()
• newMenuItemImpl(), newCheckMenuItemImpl(), newRadioMenuItemImpl() all set accelerators during creation

9.2 Accelerator String Format

GTK accelerator strings use format like:

• <Control>q - Ctrl+Q
• <Control><Shift>s - Ctrl+Shift+S
• <Alt>F4 - Alt+F4
• <Super>e - Super+E (Windows/Command key)

9.3 Modifier Mapping

Phase 10: Testing 📋 PENDING

TODO:

• Test on Ubuntu 24.04 (native GTK4)
• Test on Ubuntu 22.04 (backported WebKitGTK 6.0)
• Test legacy build on older systems
• Performance benchmarks
• Verify file dialogs work correctly
• Verify message dialogs work correctly

API Differences: GTK3 vs GTK4

Files Reference

Post-#5463 default flip — GTK4 is the default; GTK3 is opt-in via -tags gtk3 and scheduled for removal in v3.1.

GTK4 (Default) Files — built when no tag is set

v3/pkg/application/
  linux_cgo.go               # Main CGO (!gtk3 tag - default)
  linux_cgo.c                # cgo C source (!gtk3 tag - default)
  linux_cgo.h                # cgo C header (!gtk3 tag - default)
  application_linux.go       # App lifecycle (!gtk3 tag - default)
  gtkdispatch_linux.go       # GTK main-thread dispatch (!gtk3 tag - default)
  menu_linux.go              # Menu processing (!gtk3 tag - default)
  menuitem_linux.go          # Menu item handling (!gtk3 tag - default)

v3/internal/assetserver/webview/
  webkit_linux.go            # WebKitGTK 6.0 helpers (!gtk3 tag - default)
  request_linux.go           # Request handling (!gtk3 tag - default)
  responsewriter_linux.go    # Response writing (!gtk3 tag - default)

v3/internal/capabilities/
  capabilities_linux.go      # GTK4 capabilities (!gtk3 tag - default)

v3/internal/operatingsystem/
  webkit_linux.go            # WebKit version info (!gtk3 tag - default)

GTK3 (Legacy) Files — built only with -tags gtk3

v3/pkg/application/
  linux_cgo_gtk3.go          # Main CGO (gtk3 tag - legacy)
  application_linux_gtk3.go  # App lifecycle (gtk3 tag - legacy)
  gtkdispatch_linux_gtk3.go  # GTK main-thread dispatch (gtk3 tag - legacy)
  menu_linux_gtk3.go         # Menu processing (gtk3 tag - legacy)
  menuitem_linux_gtk3.go     # Menu item handling (gtk3 tag - legacy)

v3/internal/assetserver/webview/
  webkit_linux_gtk3.go       # WebKit2GTK 4.1 helpers (gtk3 tag - legacy)
  request_linux_gtk3.go      # Request handling (gtk3 tag - legacy)
  responsewriter_linux_gtk3.go # Response writing (gtk3 tag - legacy)

v3/internal/capabilities/
  capabilities_linux_gtk3.go # GTK3 capabilities (gtk3 tag - legacy)

v3/internal/operatingsystem/
  webkit_linux_gtk3.go       # WebKit version info (gtk3 tag - legacy)

Historical note: The Phase tracker blocks earlier in this document (Phases 1–4) reference the pre-flip filenames (*_linux_gtk4.go, webkit6.go, etc.) as a record of work done at the time. Those references are historical and have not been retconned; new work should reference the post-flip layout above.

Shared Files (no GTK-specific code)

v3/pkg/application/
  webview_window_linux.go    # Window wrapper (uses methods from CGO files)
  systemtray_linux.go        # D-Bus based, GTK-agnostic
  
v3/internal/assetserver/webview/
  request.go                 # Interface definitions
  responsewriter.go          # Interface definitions

Changelog

2026-01-07 (Session 11)

• Fixed GTK4 dialog system bugs
• File Dialog Fix: Removed premature g_object_unref() that freed dialog before async callback
  • GTK4 async dialogs manage their own lifecycle
  • Commit: 6f9c5beb5
• Alert Dialog Fixes:
  • Removed premature g_object_unref(dialog) from show_alert_dialog() (same issue as file dialogs)
  • Fixed deadlock in dialogs_linux.go - InvokeAsync → go func() since runQuestionDialog blocks internally
  • Fixed runQuestionDialog to use options.Title as message (was using options.Message)
  • Added default "OK" button when no buttons specified
  • Commit: 1a77e6091
• Other Fixes:
  • Fixed checkptr errors with -race flag by changing C signal functions to accept uintptr_t (3999f1f24)
  • Fixed ExecJS race condition by adding mutex for runtimeLoaded/pendingJS (8e386034e)
• Added DEBUG_LOG macro for compile-time debug output: CGO_CFLAGS="-DWAILS_GTK_DEBUG" go build ...
• Added manual dialog test suite in v3/test/manual/dialog/
• Additional Dialog Fixes (Session 11 continued):
  • Added gtk_file_dialog_set_accept_label() for custom button text
  • Added gtk_file_dialog_select_multiple_folders() for multiple directory selection
  • Fixed data race in application.go cleanup - was using RLock() when writing a.windows = nil
  • Documented GTK4 portal limitations (ShowHiddenFiles, CanCreateDirectories have no effect)
• Files modified:
  • v3/pkg/application/linux_cgo_gtk4.go - dialog fixes, race fixes, accept label, multiple folders
  • v3/pkg/application/linux_cgo_gtk4.c - DEBUG_LOG macro, alert dialog lifecycle fix, select_multiple_folders callback
  • v3/pkg/application/linux_cgo_gtk4.h - uintptr_t for signal functions
  • v3/pkg/application/dialogs_linux.go - deadlock fix
  • v3/pkg/application/webview_window.go - pendingJS mutex
  • v3/pkg/application/application.go - RLock → Lock for cleanup writes
  • docs/src/content/docs/reference/dialogs.mdx - documented GTK4 limitations

2026-01-04 (Session 10)

• Fixed Window → Zoom menu behavior to toggle maximize/restore (was incorrectly calling webview zoomIn)
• Fixed radio button styling in GTK4 GMenu (now shows dots instead of checkmarks)
  • Implemented proper GMenu radio groups with string-valued stateful actions
  • All items in group share same action name with unique target values
  • Added create_radio_menu_item() C helper and menuRadioItemNewWithGroup() Go wrapper
• Researched Wayland minimize behavior:
  • gtk_window_minimize() works on GNOME/KDE (sends xdg_toplevel_set_minimized)
  • May be no-op on tiling WMs (Sway, etc.) per Wayland protocol design
• Fixed app not terminating when last window closed
  • Added quit logic to unregisterWindow() in application_linux_gtk4.go
  • Respects DisableQuitOnLastWindowClosed option
• Fixed menu separators not showing
  • GMenu uses sections for visual separators (not separate separator items)
  • Rewrote menu processing to group items into sections, separators create new sections
  • Added menuNewSection(), menuAppendSection(), menuAppendItemToSection() helpers
• Added CSS provider to reduce popover menu padding
• Removed all debug println statements
• Files modified:
  • v3/pkg/application/linux_cgo_gtk4.go - added radio group support, section helpers
  • v3/pkg/application/linux_cgo_gtk4.c - added create_radio_menu_item(), init_menu_css()
  • v3/pkg/application/linux_cgo_gtk4.h - added function declaration
  • v3/pkg/application/application_linux_gtk4.go - added quit-on-last-window logic
  • v3/pkg/application/menu_linux_gtk4.go - section-based menu processing, radio groups
  • v3/pkg/application/menuitem_linux_gtk4.go - updated radio item creation
  • v3/pkg/application/webview_window_linux.go - fixed zoom() to toggle maximize
  • v3/pkg/application/window_manager.go - removed debug output

2026-01-04 (Session 9)

• Fixed GTK4 window creation crash (SIGSEGV in gtk_application_window_new)
• Root Cause: GTK4 requires app to be "activated" before creating windows
• Solution: Added activation synchronization mechanism:
  • Added activated channel and sync.Once to linuxApp struct
  • Added markActivated() method called from activateLinux() callback
  • Added waitForActivation() method for callers to block until ready
  • Modified WebviewWindow.Run() to wait for activation before InvokeSync
• Files modified:
  • v3/pkg/application/application_linux_gtk4.go - activation gate
  • v3/pkg/application/linux_cgo_gtk4.go - call markActivated() in activateLinux
  • v3/pkg/application/webview_window.go - wait for activation on GTK4
• GTK4 apps now create windows successfully without crashes

2026-01-04 (Session 8)

• Fixed GTK3/GTK4 symbol conflict in operatingsystem package
• Added gtk3 build tag to v3/internal/operatingsystem/webkit_linux.go
• Created v3/internal/operatingsystem/webkit_linux_gtk4.go with GTK4/WebKitGTK 6.0
• Moved app initialization from init() to newPlatformApp() for cleaner setup
• Resolved runtime crash: "GTK 2/3 symbols detected in GTK 4 process"
• Verified menu example runs successfully with GTK 4.20.3 and WebKitGTK 2.50.3

2026-01-04 (Session 7)

• Completed Phase 9: Keyboard Accelerators
• Added namedKeysToGTK map with GDK keysym values for all special keys
• Added parseKeyGTK() and parseModifiersGTK() conversion functions
• Added acceleratorToGTK() to convert Wails accelerator format to GTK
• Added setMenuItemAccelerator() Go wrapper that calls C helpers
• Integrated accelerator setting in all menu item creation functions
• Uses gtk_application_set_accels_for_action() for GTK4 shortcut binding

2026-01-04 (Session 6)

• Completed Phase 8: Dialog System
• Implemented GtkFileDialog for file open/save/folder dialogs
• Implemented GtkAlertDialog for message dialogs
• Added async callback system for GTK4 dialogs (no more gtk_dialog_run)
• Added C helper functions and Go wrapper functions

2026-01-04 (Session 5 continued)

• Completed Phase 6: Docker & Build System
• Updated Dockerfile.linux-x86_64 and Dockerfile.linux-arm64 for GTK4 + GTK3
• Added BUILD_TAGS environment variable support in build scripts
• Added Taskfile targets for GTK4 (default) and GTK3 (legacy) builds

2026-01-04 (Session 5)

• Completed Phase 5: Asset Server
• Verified WebKitGTK 6.0 uses same URI scheme handler API as WebKitGTK 4.1
• Added missing onProcessRequest export to linux_cgo_gtk4.go
• Added missing sendMessageToBackend export to linux_cgo_gtk4.go
• Confirmed asset server files (webkit6.go, request/responsewriter) are complete

2026-01-04 (Session 4)

• Completed Phase 4: Menu System
• Implemented GMenu/GAction architecture for GTK4 menus
• Created GtkPopoverMenuBar integration
• Added menu_linux_gtk4.go and menuitem_linux_gtk4.go
• Added gtk3 build tags to original menu files
• Implemented stateful actions for checkboxes and radio items

2026-01-04 (Session 3)

• Completed Phase 3: Window Management
• Implemented GTK4 event controllers (GtkEventControllerFocus, GtkGestureClick, GtkEventControllerKey)
• Implemented window drag using GdkToplevel API (gdk_toplevel_begin_move/resize)
• Implemented complete drag-and-drop with GtkDropTarget
• Fixed window state detection (isMinimised, isMaximised, isFullscreen)
• Fixed size() function to properly return window dimensions
• Updated windowSetGeometryHints for GTK4 (uses gtk_widget_set_size_request)

2026-01-04 (Session 2)

• Completed Phase 2: Doctor & Capabilities
• Updated all 7 package managers for GTK4/WebKitGTK 6.0 as primary
• Added GTKVersion and WebKitVersion fields to Capabilities struct
• Created capabilities_linux_gtk3.go for legacy build path

2026-01-04 (Session 1)

• Initial implementation of GTK4 build infrastructure
• Added gtk3 constraint to 5 existing files
• Created 5 new GTK4 stub files
• Updated UNRELEASED_CHANGELOG.md