Comment 38 for bug 684982

In my experience, on Gnome or KDE every GUI window (not only from Mozilla) opens on whichever virtual desktop is current at the time the window opens. In particular:
- if I start a GUI application from a desktop shortcut icon or an xterm then quickly change virtual desktops, the GUI will open on the new virtual desktop;
- an alert popup relating to some window on a non-current virtual desktop may appear on the current one if it is "floating" (like our Preferences dialog) and not "tied to its window" (like the SeaMonkey button palette).

This happens to me the same way for every GUI, be it Firefox, Vim, LibreOffice, some KDE game, whatever.

However:
When logging out of X11 with some GUIs still open, then some window managers can restore them to the right virtual desktop at the next X11 login. (KDE window managers can even restore gvim compiled with the Gnome session restore feature built-in.) This of course does not apply to Mozilla apps as long as the preferred closedown method for them is Ctrl+Q or File→Quit rather than letting them be closed forcibly by the window manager.

I don't know anything of MacOs with or without X, and I left Windows for good at a time when XP SP2 was state-of-the-art so I'm not going to talk about them.