X.Org X Server 1.12.3
ATI with fglrx driver
Broken: tested 2.78a and 2.78c
Worked: 2.77 #22a2853
Short description of error
if you have seperate xscreens (:0.1, :0.2, :0.3) and pan the view with middlemousebutton in blender running on screen :0.0 for example. the cursor can get grabbed by another screen, for example :0.1
but imho cursor should end up where the panning got started?!
Exact steps for others to reproduce the error
as described above, works with any file...