I would also like this, its annoying to have so many things open on the taskbar, and I don't really want people to glance at my screen and be able to tell instantly whether or not I opened private browsing, its not very private if they can see.
Reallow us to put private windows under the same taskbar icon
It seems the preference was disabled in one of the recent updates so that setting "browser.privateWindowSeparation.enabled" to "false" no longer works, I'd like it if it was re-allowed to ...
