When you disable a Xinerama screen (think of removing a video projector),
the workspaces of that screen need to be re-assigned to another screen.
Previously, the clients affected by this re-assignment did not get re-
configured, which made them appear on the next screen which got configured
at the position of the old one again if you did not switch to the reassigned
workspace before.
So, to reproduce it:
xrandr --output VGA --mode 1280x1024 --right-of LVDS
move windows to the new workspace
xrandr --output VGA --off
xrandr --output VGA --mode 1280x1024 --right-of LVDS
This fixes ticket #36
18da0a3017