I sometimes drag tabs from my main window to my second monitor and I do that by dragging to the left site - which is also where AiOS is placed. AiOS is then opened and the newly created window (by dragging the tab into empty space) will also have AiOS opened, so I have to close them both, which is really annoying.
This works when draggin anthing, including dragging nothing (e.g. clicking down on the empty space in TreeStyleTab an then dragging to the left side) but not when making a selection. This is probably because the mouse gets locked by FireFox.
I work around this for now by having AiOS on the right but it's still an issue.
AiOS issue: AddonLab/AiOS#34
[x] Add necessary prefs for this and adjustments to code