User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729) Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729) I have a three monitor setup in Vista x64. The monitors are set up like so: 1 (Left) <-> 2 (Center / Primary Display) <-> 3 (Right). If I have one Firefox window open (say primary monitor (#2)) and want to move a tab to another monitor which has no Firefox window, I drag the tab to desired monitor and drop it. A new window is created with the tab (sweet!) but often it displays on the wrong monitor. For example, if I have only one Firefox window open (lets say its on my main monitor: #2) and drag a tab to another monitor (say #1), that tab may end up on monitor #3. Reproducible: Sometimes Steps to Reproduce: 1. Get access to a machine with atleast three monitors. 2. Open Firefox such that only one Firefox window is open 3. Open a few tabs (the websites shouldn't matter) 4. Drag a tab to a monitor where no Firefox window exists and "drop" the tab Actual Results: The dragged tab will often appear in a new window on the wrong monitor (not the monitor I dropped the tab on). I haven't yet spent enough time to understand if there's a specific pattern to when exactly it happens, but it probably happens about 50% of the time for me. Expected Results: The dragged tab should appear on the screen it was dragged to

If its not clear from the User Agent/Build ID above, this is on Firefox 3.5rc2

I've only used multiple monitors a few times (so forgive me if I'm screwing up the wording). Do you have the settings set to extend the desktop on all three monitors or do you have the settings set to replicate the desktop on all three?

Thank you, good question :) All three monitors display separate windows- that is, monitor 2 has the "This is my main monitor" checkbox checked in the display settings while 1 & 3 have the "Extend the desktop onto this monitor" setting enabled. See attached monitor-settings.png.

on XP using 2 monitors, i can't drag a tab off and drop it on the other monitors desktop. (dual mode, latest FF 3.5.1) The window always opens in the main window.

maybe relates to bug 465186