Loss of focus while dragging floating windows (inspector/mixer)

Anyone else notice this? It happens when the mouse moves not slowly upon one of the floating windows (inspector/mixer/etc.) and strangely, if the mouse is let up,it still acts sometimes like it's being dragged. The following video-clip might not be adequate -- it doesn't show the left mouse-button being held down or let up, just a pressing, but it might help to demonstrate the issue. Something funny's going on with the Qt focus code or something utilizing it: probably an easy fix somewhere:

Hope it's not just this system. Please verify if possible.