Frame Buffer Render Region "moves"

[OPEN_RANGE]

Not really a problem but I am noticing a new behavior. I render a scene in VFB and then I draw a render region. If I click inside the region, the area within the region moves slightly to the left. If out of the region, it moves back into original position. Turning the region on and off or clicking in the VFB in or out of the region causes this slight but noticeable movement form side to side.Strange.