I've got a small idea. You have now many different tool windows. It's cool, but I have to find "close" button in each window every time I want to close it. Even in similar windows (messages for example) they are in different place, etc.
Is it possible to move "close tool window" button to a similar place in all windows, or even to a titlebar? I think it will be much better to have it every time in same place.