Vidalia 0.3.1 detaching tabs moves their tile bar out of the screen
On Windows 7 64bit, the "tor-browser-2.3.12-alpha-1_en-US" detaching tabs moves their window to the upper left corner of the screen.
This is done in a way where their title bar is out of the actual screen. Therefor the window can't be moved. The workaround is to resize the window to see the title bar and move the window around.
Note that the window just has to resized about 1 or 2 pixels and Windows 7 moves the window itself so that the title bar appears.
An IRC client can detach windows as well and with that the problem does not appear.