If there is an instance of Firefox running on a computer with only one monitor attached, and you then attach a second monitor and use the "xrandr" command line utility to activate it as an expansion of the desktop (not a clone), and either move the Firefox window to the second monitor or open a new window on the second monitor, then application menus and text completion dropdowns triggered by that window will appear at one edge of the first monitor rather than in the appropriate place on the second monitor. Note that it does *not* happen for dropdown widgets (<select> in HTML) -- are those perhaps not being rendered as Gtk menus? They look subtly different from the dropdowns that suffer the bug. This is probably specific to X Windows and perhaps even to xrandr-1.2 rather than older multi-monitor X extensions. I don't have any way to test it on something else, though.

I should have mentioned that this bug persists until you restart the browser, and that it doesn't happen if you start the browser after both screens are active.

... also, just discovered that tooltips suffer the effect too.

This is reproducible on Minefield Latest nightly build (as of 11/Mar/2009) on Windows Vista as well. Restarting the browser will fix it momentarily, but within a few seconds or minutes the menus start "leaking" from over to the primary monitor, even if minefield is fully dragged over to the secondary. All the menus, contexts, tooltips, dropdown completions, etc spill over to the primary display.

Reproducible also on XP. Is consistently happening in both normal and safe mode.

This started happening on Mac OS X with the nightly I downloaded and installed this afternoon.

Does this happen to people other than me all the time, or just when a second monitor is activated while Minefield is running?

(I only see it when the second monitor is activated after FF is running, just to be clear.)

Dup of bug 482928? Regression range is wrong, although the latest comments might be the wrong bug?

I'm experiencing a very similar problem... with tooltips, right-click menu, main menu, url completion. I've attached 2 screenshots, firefox maximized in secondary screen. What is strange is that when I right click on the left part of the secondary screen --> menu showed on primary screen (the bug). But when I right click on the very right of the secondary screen --> menu displayed correctly. Exact same behavior with Thunderbird. Restarting FF or TB doesn't help.

Additionnal note : no problem with FF on primary screen. I also tried changing primary screen, then restarting FF --> same behavior. Other apps like Chromium browser are displaying popup menus correctly on secondary screen.

(In reply to Marc MAURICE from comment #11) > I've attached 2 screenshots, firefox maximized in secondary screen. My mistake : it's not maximized on the screenshots, but I experience the same behaviour, either maximized or not.

Hey, I took the source today and played a bit with it. I got more info on that bug : * this is linked to firefox zoom value. As I have a High DPI screen, I set layout.css.devPixelsPerPx to 1.5. Resetting it to the default value and the bug is gone. however, everything is so small ! * in widget/gtk/nsScreenManagerGtk.cpp, ScreenForRect function is returning the wrong screen * the widget coordinates given as arguments are wrong (aX and aY), probably due to the modified zoom. any clue on that ? plz ?

Tried changing some settings as https://wiki.archlinux.org/index.php/Firefox_tweaks#Configure_the_DPI_value No success...

Problem still here in FF version 29.

This is a screenshot of the bug appearing in TB 38.7.2 under Linux Mint 17 Qiana