UPDATE For your convenience, I've uploaded the scripts and alternate icon so you can download them yourself. This week, Mozilla released the much-anticipated Firefox 1.5 upgrade. While I'd love to start playing with the new features (SVG, fast forward and back, etc. etc. etc.), I need to be able to test in Firefox 1.0.x. Enter MOZ_NO_REMOTE. MOZ_NO_REMOTE allows you to run multiple versions and/or profiles of Firefox at once. The only downside, and this is a big downside, is that every time I launch a shortcut or open an HTML file, I get prompted by the Profile Manager to pick my profile. In the words of Cartman, Lame. Not cool. Hoping for a solution, I hopped onto #firefox at irc.mozilla.org and the good folks there pointed me to a solution: run the new version via a batch file. After a little experimenting, I've gotten the best results with the directions that follow. (Note that this is aimed at folks who have Firefox 1.0.x installed as their default browser and want to keep it that way, at least for the time being.)

1. Download Firefox 1.5 and install it to somewhere other than the default Firefox location (I'll assume you used C:\Program Files\Mozilla Firefox 1.5). When it asks you if you want to launch Firefox, just say no.
2. Browse to C:\Program Files\Mozilla Firefox 1.5 and make a copy of firefox.exe as firefox1.5.exe. (I'm not sure if this step is necessary, but it is nice to be able to view the differentiate between the running processes in the Task Manager.)
3. Fire up your favorite text editor and create the following script:

   set MOZ_NO_REMOTE=1
   start "Firefox" "C:\Program Files\Mozilla Firefox 1.5\firefox1.5.exe" -P "Firefox1.5"
   set MOZ_NO_REMOTE=0
   

   Save it as Firefox1.5.bat.
4. Run the batch file. (Some spyware/anti-virus products will ask you if you want to grant the file permission to run, click Yes.)
5. The profile manager will appear. Create a new profile named Firefox1.5. From here on out, it won't ask you for a profile.

If you're like me and you hate the cmd window that shows up whenever you are running Firefox 1.5 and have cygwin, you can modify the script to run from cygwin and promptly ending. Nevermind that problem, thanks Eugene. But, if you still want to run it from cygwin...

#!/bin/bash

MOZ_NO_REMOTE=1
export MOZ_NO_REMOTE
/c/cygdrive/Program\ Files/Mozilla\ Firefox\ 1.5/firefox1.5.exe -P "Firefox1.5" &
MOZ_NO_REMOTE=0
export MOZ_NO_REMOTE

I've saved it as /usr/local/bin/ff15 and it'll launch whenever I run ff15 from the command line. That's that! I hope some folks find this useful. Add an icon If, like me, you want to be able to easily differentiate between a Firefox 1.5 and Firefox 1.0 window, you can grab my tweaked main-window.ico and place it in C:\Program Files\Mozilla Firefox 1.5\chrome\icons\default. I also highly recommend the Titlebar Tweaks extension which allows you to cuzomize the window titlebar. By the way, if anyone knows how to make windows batch files run Firefox and continue on (which & will accomplish for you in UNIX land), please post a comment! Thanks, Eugene. :)