New to 4.5a5, did not occur in 4.5a4:
Tor Browser window frantically resizes sometimes. For instance, if I try to resize the window, it oscillates between two sizes for a few seconds, until stabilizing. Sometimes it uses the new size and sometimes it reverts to the current size.
Also, the window has been observed to follow me across desktops. I change desktops and after about a second the Tor Browser window appears.
Using Debian 7 with XFCE.