[macOS/Windows] Implement live wallpaper mode.

[bruvzg]

Adds window flag to move window to the desktop level (above wallpaper, below desktop icons).

Implements godotengine/godot-proposals#5388 for Windows and macOS.

Updated version of the POC from godotengine/godot-proposals#5388 (reply in thread)

	get_window().borderless = true
	get_window().wallpaper = true
	get_window().position = DisplayServer.screen_get_usable_rect(0).position
	get_window().size = DisplayServer.screen_get_usable_rect(0).size

macOS:

Screen.Recording.2025-05-16.at.09.54.22.mov

Windows 11:

Recording.2025-05-16.104713.mp4

[Calinou]

Tested locally, it works as expected.

Testing project: test_live_wallpaper.zip

Example on macOS 15.4.1 (with maximized window, pure black wallpaper, dock is autohidden so it appears fullscreen):

Some feedback:

• Per-pixel transparency works. That said, you could also fetch the user's current wallpaper using OS APIs and apply it as a background to your project using a TextureRect, which is more efficient, more reliable and won't prevent you from using effects that only work with opaque viewports.

• If you only enable the wallpaper flag, the window borders will still be visible, but you can't interact with them (even if you alt-tab to focus the window). Should we make this flag also force the window to be borderless at the same time?

• Should we have wallpaper as a project setting, so you can enable it without needing a script? This would also allow us to warn users that it won't work when game embedding is enabled, similar to the fullscreen window mode.

• For a live wallpaper that covers the whole screen without changing workspaces on macOS, it seems you need to use the Maximized window mode, not Fullscreen or Exclusive Fullscreen. I'm curious how you can make the live wallpaper cover what's behind the dock/task bar though (since these are translucent by default).

[shitake2333]

Providing relevant project settings is very necessary.