Vertical position of mouse cursor is set incorrectly when releasing windows from corner and top/bottom half grid positions (Regression)

[Esokrates]

This bug is regression (did not happen in Quantal):

If you drag off a window positioned in corners or top/bottom half by dragging vertically, the vertical position of the mouse cursor gets set incorrectly (when releasing windows on the bottom workspace edge, the cursor gets positioned under the title bar and vice versa for windows on the top edge).
However, if you drag the window off horizontally, the vertical position of the cursor is set correctly.
The following video demonstrates this:
http://ubuntuone.com/59ZATAb59Nn380ybzjRR13