Better MGSE Multi Monitor Support.

Clone the top and the bottom panel to all active displays. the bottom panel on every display should only show open applications of the specific display the bar is on. actually if we're working on for example display three, we have to move the mouse through display two into display one to open the mint menu or the gnome menu (left top corner). multiple displays are increasing productivity highly, but gnome 3 destroyed it because we have to do a lot of long mouse-ways now.