Let me reiterate - OPERA IS THE BEST BROWSER YOU CAN FIND!
but when you are into web development you have to resort to firefox often for the add-on. Funny though that since addon have started appearing I have stopped seeing progress in firefox, its memory heavy, cpu heavy, slowest browser that is now just for Google promotion - The very reason for its existence.
Anyhow I am quite used to opera where pressing ctrl+H send it to system tray, freeing the task bar space. So I thought may be someone at firefox is trying to copy that too. But no, finally had to get an add-on (an unsigned addon that carries as much security risk as anything else) to minimize firefox to the system tray.
Here is the link to it -
To customize this add-on, go to Tools menu of Firefox and the n click Add-ons.
Now select Minimize to Tray Add-on and click options.
This will open the options window. Check the options you like.
Click ok and you are done.
Works could have been inbuilt in firefox!
Till the time firefox itself becomes anything worth competing with Opera or Even Flock you'll have to rely on addons.