X11: fix window placement on multi-monitor setups
X11: avoid probing hw on query xrandr
X11: remove some unnecessary XSync calls
X11: do not trust XQueryPointer right after an XRR event
X11: position pointer in the center of the window if last position is not known
X11: hide mouse on initial creation of window
Merge pull request #5277 from FernetMenta/X11

X11: fix window placement on multi-monitor setups