This only works with the userspace build of SharedGraphics so far.
It's also very slow at loading fonts, but that's easy to fix.
Let's put fonts in /res/fonts/.
To start painting, call:
gui$get_window_backing_store()
Then finish up with:
gui$release_window_backing_store()
Process will retain the underlying GraphicsBitmap behind the scenes.
This fixes racing between the WindowServer and GUI clients.
This patch also adds a WSWindowLocker that is exactly what it sounds like.
