Running Firefox 3 and Firefox 2 simultaneously

Well I usually have a ton of tabs open on my Firefox. One of the sad things I found on trying to upgrade to Firefox 3 Beta 2 was that most of my extensions just stopped working.

So I decided to stay with Firefox 2 as my main browser, till at least Tab Mix Plus starts working.

The problems I found ere:

1. Running Firefox 2 while 3 was running or vice versa would open another window in the currently running version.
2. Running one after the other would clear all my cookies in the case of the downgrade (i.e. 3 --> 2) and force reload all the pages (as it does after a crash) i.e. a HUGE waste of time

So I looked for a bit of help, and did the following things:

1. Started the profile manager and created a new profile for Firefox 3, "f3"
2. Since the profile manager does not allow copy profile and I wanted all my settings to go to Firefox 3 with me, I copied all the data from the Firefox 2 profile ("default") to f3.

On Windows, this can be found in %USERPROFILE%\Application Data\Mozilla\Firefox\Profiles

The profile folder name is random, the extension is the actual name of the profile. BTW, the same folders exist in %USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Profiles also, but these are used for the disk cache.

Now to the running part. The issue is, once you select a profile with the profile manager, both versions will use it. So, what you have to do is pass the profile name to Firefox as well as a flag telling it to allow multiple instances. With a little help from the Firefox KB, I altered my Firefox shortcuts to say the following:

Firefox 3:
"E:\Program Files\Mozilla Firefox 3 Beta 2\firefox.exe" -P f3 -no-remote

and

Firefox 2:
"E:\Program Files\Mozilla Firefox\firefox.exe" -P default -no-remote