Previously we were rendering the whole menubar on every compose(),
even if nothing changed about it. Now it's in its own window and can
be invalidated and painted separately.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
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. :^)
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. :^)
