[GAMEPLAY] Item Shop - stuck when draging it out of the screen

When draging the item shop out of the bottom border of the screen it keep stuck there somehow. When you try to drag it back towards the center of the screen the item shop windows moves up just some millimeters (not following the mouse until the end of my movement). it takes several times until the shop is in the center again, by moving it step by step. Draging the item shop out of the left or right border has no issues.

• Drag the item shop window out of the screen (bottom border)
• try to drag it back.

This bug is always reproducable for me. Bug happens on mac OS X 10.10 and Windows 8.1.