The enabled state of a GAction now propagates both to any toolbar buttons
and any menu items linked to the action. Toolbar buttons are painted in
a grayed out style when disabled. Menu items are gray when disabled. :^)
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. :^)
Now that everything is nice and mature, the WindowServer can just use the
client PID it receives in the Greeting message, and we can get rid of this
hacky ioctl. :^)
