When resizing a window, we often end up having to paint some part of it
without coverage in the current backing store. This patch makes those cases
look nicer by having a fallback background color for each window, passed
along with the CreateWindow client message.
Any GWidget can have a tooltip and it will automatically pop up below the
center of the widget when hovered. GActions added to GToolBars will use
the action text() as their tooltip automagically. :^)
These events are identical, so it's silly to send both. Just broadcast
window state changes everywhere instead, it doesn't matter when it was
added as clients are learning about this asynchronously anyway.
I originally thought I would do this inside WindowServer, but let's try to
make it as a standalone app that communicates with WindowServer instead.
That will allow us to use LibGUI. :^)
