I am running SysInternal's Desktops 1.02 and FireFox 3.6.2. I have noticed that while I can have Internet Explorer 8 open in multiple virtual desktops, you can not do the same with Firefox. If you try you get the error message:
Firefox is already running, but is not
responding. To open a new window, you
must close the existing Firefox
process, or restart your system.
I did a little digging around to work around this and came up with creating a second profile via the Firefox profile manager (accessed by starting Firefox with the "-p" switch). This unfortunately created a new problem which is my add-ons (of which I use many) do not stay synchronized between profiles.
Is there a better approach here?
Best Answer
With the Sysinternals utility, Firefox on another desktop runs as a different process, just as if you had run it as:
(That usage will also complain if you try to use the same profile twice, even if you're not running Desktops).
It looks like Firefox is using Windows messages to determine whether there's already a Firefox instance running, and doesn't find anything on the same desktop, so starts a new instance.
And this is why you can't use the same profile.
I'm guessing that IE8 works differently (possibly because it uses multiple processes anyway) and uses some communication mechanism that works across multiple desktops.
IE8 probably co-ordinates all access to user (profile) data through a single process; Firefox doesn't, so it will prevent multiple processes using the same profile to avoid the possibility of file corruption.
Alternative
VirtuaWin, available free from Sourceforge, does essentially the same job, and works the way you'd expect with Firefox - multiple Firefox windows across various desktops, all from the same Firefox instance with the same profile.