Grid: Dragging screen centric windows (e.g. "Sim unlock required") causes cursor being changed relative to the window

If you resize a window which default position is set to the middle of the screen, for example the "SIM PIN Unlock required" window, it gets moved the center of the screen.
If you position the window and drag it off from grid positions the mouse cursor changes relative to the window (Dragging it off moves the window instantly to the center while the mouse pointer keeps its position), which is unwanted behaviour.
Dragging off these windows used to work in Quantal for semi-maximized and maximized state, but back then another bug appeared for semi maximized state which is now gone: the horizontal width of the window was not correctly reset.
After the mouse pointer was set (to drag off the window), the location of the reset window should not change.
The following video demonstrates this behavior:
http://ubuntuone.com/1MYUTOAYKqGGdiijKZZZag