Only set the screen right before triggering show(), otherwise it can mess
up for reasons I don't know.
Also I prefer not to pass the screen in the constructor, given that we
move the DesktopView instances across screens and it gives the wrong
impression that the view is tied to the screen.
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
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.
Aleix Pol
Vishesh Handa
Marco Martin