WinXP + IE8
DebugBar detached.
Open Script tab.
When the mouse goes over ANY part of the "<Main document>" row, it highlights the document in IE8 and the IE8 window is focused, putting DebugBar underneath it.
There is no hover delay, it happens immediately. This means that normal mouse movements trigger it and "hide" the DebugBar window underneath the IE8 window.
It took several minutes to figure out WTF was happening.
This makes the entire Script tab a PITA to work with, especially with a small desktop size. You have to constantly be mindful of not hovering over this special row or deal with re-focusing the DebugBar just because you had to move your mouse from the top of the window to the bottom.