Slow respons when closing submenus

Just discovered other strange behaviour:

- Open a virtual folder in the TLB which contains a submenu, open this submenu too;
- Hover the mouse quickly over another virtual folder in the TLB; the first opened menu will close automatically and the item where the mousepointer hovers opens;
- Move the mouse quickly to the first menu again. It will open shortly, but it closes immediately, leaving some parts of the menu on the screen.