Kotlin Window Management library

Kotlin Window Management is a library that wraps OS-specific window management APIs into an idiomatic Kotlin interface.

The library serves as a foundation for the UI framework used in Air and will later provide an OS integration layer for Compose for Desktop.

Goals

• Provide a simple Kotlin API for OS features needed to build desktop applications
• Support all major desktop platforms: Linux (both X11 and Wayland), macOS and Windows
• Flatten OS quirks or at least document them
• Provide a safe API. Incorrect usage of the API should lead to Kotlin exceptions but not crashes
• Provide rendering contexts compatible with Skia, e.g., via skiko
• Make it Kotlin Multiplatform in the future

Non-Goals

• Providing bindings for Android or iOS, they are too different from desktop
• Bindings for browser APIs
• API alignment across platforms. Desktop platforms differ in their capabilities; we do not intend to hide these differences

Status

✅ - implemented

🚧 - in progress, partially implemented

❌ - not implemented yet

➖ - not applicable

Application

	MacOS	Wayland	Windows	X11
Run event loop	✅	✅	✅	✅
Invoke on Main thread	✅	✅	✅	✅
List screens	✅	✅	✅
Terminate application	✅	✅	✅	✅
Show notification	✅	✅	❌	✅
System tray	❌	❌	❌	❌
Application icon	✅	➖	🚧	❌
Application menu	✅	❌	➖	❌
Accessibility	❌	❌	❌	❌
File choose dialog	✅	✅	🚧	🚧

Window

	MacOS	Wayland	Windows	X11
Position	✅	➖ (startMove)	✅	❌ (startMove)
Size	✅	➖ (startResize)	✅	❌ (startResize)
Max/Min size	✅	✅	✅	🚧 (setMinSize)
Content size	✅	➖	✅	❌
Current screen	✅	✅	✅	❌
Full screen	✅	✅	❌	✅
Maximize/Minimize	✅	✅	✅	✅
Request focus	✅	✅	🚧	✅
Set cursor icon	✅	✅	✅	✅
Transparency	✅	✅	✅	✅
Background effects	✅	❌	✅	❌
Close window	✅	✅	✅	✅

Rendering

	MacOS	Wayland	Windows	X11
Metal	✅	➖	➖	➖
ANGLE	❌	❌	✅(DX11)	❌
DirectX12	➖	➖	❌	➖
OpenGL	➖	✅	❌	✅
Vulkan	❌	❌	❌	❌
Software	❌	✅	✅(WARP)	❌

Events

	MacOS	Wayland	Windows	X11
KeyDown	✅	✅	✅	✅
KeyUp	✅	✅	✅	✅
ModifiersChanged	✅	✅	➖	✅
MouseMoved	✅	✅	✅	✅
MouseDragged	✅	❌	❌	❌
MouseEntered	✅	✅	✅	✅
MouseExited	✅	✅	✅	✅
MouseDown	✅	✅	✅	✅
MouseUp	✅	✅	✅	✅
ScrollWheel	✅	✅	✅	✅
WindowSizeChange	✅	✅	✅	✅
WindowResize	✅	✅	✅	✅
WindowMove	✅	➖	✅	❌
WindowFocusChange	✅	✅	✅	✅
WindowCloseRequest	✅	✅	✅	✅
WindowFullScreenToggle	✅	✅	❌	✅
WindowChangedOcclusionState	✅	❌	🚧	❌
DisplayConfigurationChange	✅	✅	🚧	❌
ApplicationOpenURL	✅	✅	✅	✅
ApplicationAppearanceChange	✅	✅	✅	✅
ApplicationDidFinishLaunching	✅	✅	✅*	✅

* On Windows, a callback is currently enqueued before starting the event loop. This may be replaced with an ApplicationDidFinishLaunching event in the future.

Theme

	MacOS	Wayland	Windows	X11
isDark/isLight	✅	✅	✅	✅
Sync with OS	✅	✅	✅	✅

Input Methods

	MacOS	Wayland	Windows	X11
Custom text input context	✅	✅	❌	✅
Order emoji popup	✅	➖	❌	❌

Clipboard

	MacOS	Wayland	Windows	X11
Simple text copy/paste	✅	✅	🚧	✅
Copy files	✅	✅	🚧	✅
System defined clipboard types	✅	➖	❌	✅
Custom binary clipboard content	✅	✅	❌	✅
Lazy fetch of clipboard content	❌	✅	❌	✅

Screen

	MacOS	Wayland	Windows	X11
ScreenId	✅	✅	➖	✅
IsPrimary	✅	❌	✅	❌
Name	✅	✅	✅	✅
Origin	✅	✅	✅	✅
Size	✅	✅	✅	✅
Scale	✅	✅	✅	✅
FPS	✅	✅	✅	✅
Color space	❌	❌	❌	❌
Persistent identity	✅	🚧	❌	❌

Drag and Drop

	MacOS	Wayland	Windows	X11
Window as drag target	✅	✅	❌	✅
Drag entered	✅	✅	❌	✅
Drag updated	✅	✅	❌	✅
Drag exited	✅	✅	❌	✅
Drag performed	✅	✅	❌	✅
Drag source	✅	✅	❌	✅

Acknowledgements

Many libraries tackle the same problem from different angles, but each makes slightly different trade-offs compared to KDT.

To name a few:

• AWT
• gpui.rs
• JWM
• JavaFX
• GLFW
• SDL
• Electron