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I'm using the normal Firefox 3.5.3 right now, but sometimes I read about some features that work in the development version(nicknamed Minefield) and I would like to take a look at them.

To that end, I've downloaded the .zip file with the latest dev-version from the mozilla servers.

Problem is that after I unzipped it and try to start it, what happens is that the current running instance of my normal Firefox is opened.

Does anybody know how to remedy this problem?

share|improve this question
Do you need them both open at the same time? – Sasha Chedygov Oct 4 '09 at 20:50
I don't want to close the normal one, but I would like to check out the special features of the development version. – KdgDev Oct 4 '09 at 21:10
up vote 2 down vote accepted

the beauty of Sandboxie ...

every now and then i grab the portable version of the latest build (currently and run it in a separate sandbox.

not only can i run both browsers side by side simultaneously, Sandboxie also makes sure that no half-baked pre-release will ever make any permanent changes to the windows registry or may otherwise cause harm to the system, a win-win situation. :)

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That's really cool! Didn't know something like that existed. +1 – Sasha Chedygov Oct 4 '09 at 20:53

Firefox, when run normally, always looks for already present instances and doesn't open a new one if any is present.

However, You can bypass this behaviour by running a command (You can even make a shortcut to it):

firefox -no-remote -P PROFILE_NAME

You can create a profile by executing first:

firefox -P

(You should have a separate profile for the second instance of Firefox).

share|improve this answer
I use this method for playing flash games. my normal profile loads flashblock and other stuff for locking down the browsing session. if i find one of the myriad flashgames out there that i like to play, i load a testing profile and add a bookmark to that site. if the game crashes the flash plugin (and thus the browser), my main browser session is unaffected. – quack quixote Oct 5 '09 at 1:55

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