On one desktop I keep three Konsole windows open all the time, as in the 
screen shot attached. I've found that I cannot move the central window to the 
vertical centre of the screen: as I drag it up, or down, to the centre it 
stops moving for a while and then jumps to a position beyond the centre.

Hardly an earth-shattering problem, but I wonder what causes it...

-- 
Regards,
Peter.