This patch introduces the second MenuApplet: Audio. To make this work,
menu applet windows now also receive mouse events.
There's still some problem with mute/unmute via clicking not actually
working, but the call goes from the applet program over IPC to the
AudioServer, where something goes wrong with the state change message.
Need to look at that separately.
Anyways, it's pretty cool to have more applets running in their own
separate processes. :^)
Instead of implementing menu applets as their own thing, they are now
WSWindows of WSWindowType::MenuApplet.
This makes it much easier to work with them on the client side, since
you can just create a GWindow with the right type and you're in the
menubar doing applet stuff :^)
