Fix panel, app switcher, and looking glass to limit themselves to the
primary monitor, and run dialog to limit itself to the monitor
containing the currently-focused window.
The overview is also limited to the primary monitor now (with the
other monitors being blacked out), although the workspaces within the
overview are shaped like the full "screen" (the bounding box of all
monitors). To be fixed later.
https://bugzilla.gnome.org/show_bug.cgi?id=593060
2b78d5bd5d