Shuffle around some menu related code from window manager into menu
manager. This still is not perfect, and results in a little more of the
window manager to be publically exposed - but this is another step
towards better seperation of concerns between menu and window manager.
We also move the mouse_event handling into a new function in menu manager
as event handling was beginning to become a bit chunky.
If the window switcher is up when a window is made frontmost (usually
by clicking on it), the window will now become the selected window in
the switcher.
This still has a slight feeling of "hmm" but is definitely better than
what we had before.
Move applet logic to the own class. Remove applet code from MenuManager.
With new AppletManager applet order is configurable via WindowManager.ini file.
