this makes the desktops and panels more deterministically
follow the primary screen
* adaptToScreen is useless per se in moveEvent, but what's worse will cause a recursion loop
* disconnect the geometry sync from the old screen
CCBUG:335710
since people find it too weird, hide dashboard from task manager
*but* it's going to stay under the panel, and windows are still
going to be capable to cover it
BUG:332691
Set all the winId dependent stuff whenever it changes, windows are recreated
upon screen change and we need to make sure the set properties are
honored after changing screens.
Marco Martin
Aleix Pol