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. :^)
