Previously it was only possible to change these window attributes when
creating a new window. This patch adds an IPC message that allows you
to change them at runtime.
We were not repainting windows that were occluded at the time of the
theme changing. This patch adds a way to bypass occlusion testing when
invalidating window rects.
Fixes#1249.
This patch removes the internal system menu from WindowServer and
replaces it with two IPC API's:
SetSystemMenu(menu_id)
SetSystemTheme(theme_path, theme_name)
These API's will allow us to complete the SystemMenu program and
move it entirely out of process.
