Is opening a new window too hard?
We've been given this most absolutely fabulous of devices known as a brain which is empowered with the most amazing ability to sort, organize and multitask
Now, with that in mind, Firefox has, since its beginning, allowed multiple instances to be run at once. I know, I know, I'm committing heresy by insinuating that perhaps we should - shock! gasp! - use our operating system as intended, but perhaps we could put just a tad bit of our superior intellect to work and... organize windows based on intended tab subject. For instance, I'm looking at The Register, an article reminds me that I want to research SLRs, I open a new window and then a tab to Wikipedia, then a new tab to Google to search for DSLRs, then tab out whatever shopping links or reviews from them.
Again, heresy! Of course, it could be said that Firefox could be dedicating its UI designers to a vastly more useful purpose, like unfucking just about everything they've been doing since Firefox 3, but I'm deathly afraid of what they'd do to actual code written by real programmers... if Firefox could be said to have any of those anymore.
Please don't mistake me for an Opera fanboy - those guys really get on my tits - but Firefox has been suffering from a self-inflicted syndrome, that of being a keystone predator. It hasn't had any natural enemies until Microsoft stepped up IE in the last year, and they've gotten lazy. They're well funded by Google and can shove out all the shitty, bloated code they want because there was no alternative (yeah yeah, sod off fanboys, nobody cares).
The lack of tabs was a legitimate problem, as was that of plugins running within the same process as the browser. Misuse of tabs isn't the fault of the operating system or browser, it's one of the few true instances of PEBKAC.