Pushing the envelope in terms of interface is a really tricky thing to do. Each time you do it, there's a huge user outcry, and it does turn some users away or stops them from upgrading. I don't think the Firefox feature announced here will be much different.

People like things to stay the way the are used to. Unless there's a huge change and they can see how dropping their old habits all at once is somehow an advantage.

Gradually adopting improved versions of the most sensible Chrome features might sound like sound engineering, but due to these dynamics I really wonder if its a survivable strategy in the long run.

There were some UX mockups posted a while ago that looked far more ambitious. That's more like it.

It's true, yet I think it still needs to be done, even though I'm often among the complainers. The key is balance: advancing UI without forcing users that are looking for a solid consistent experience to beta test your UI ideas. Ubuntu is an example of a lot of really bold UI decisions, and I think they're too eager to force things on users. Ubuntu is in the tricky situation of making a product for "the hard-core" (Linux geeks) and "the noobs" (non-tech-savvy users wanting a free OS).

And the reason I like Firefox is because there's always a way to go back to the old behavior/UI without losing the benefits of the new underlying system. That is respectful to users, as opposed to the Chrome way where you take it or leave it at a corporation's whim.

A presentation on it here: http://www.slideshare.net/BrendanEich/future-tense-7782010

Of course, students of history will remember what happened the last time that Mozilla/Netscape tried rewriting their browser engine: http://www.joelonsoftware.com/articles/fog0000000069.html

Hopefully things will go a bit more smoothly this time. :)

And of course this is all just research at this point, none of this might ever see an actual release.

Well it's not a universal rule to never scrap code. Sometimes the software is just so bad, so complicated, so wrong for the task that it must be scrapped. Large parts of Navigator, but also other things like OS 9 are examples. The original Mac OS was simply not cut out for an internet age -- like Windows 9x it couldn't be reworked to something current.

Even if Mozilla fails to keep their browser relevant, the investment is sure to pay off with a new widely respected system programming language. If you follow the reception of Rust virtually everybody seems impressed with the rationality and practicality of its design choices, explained and backed by solid engineering. Compared to the nearly universally panned golang (series of arbitrary decisions) or even Dart (decisions not backed by metrics), it's hard to imagine that Rust won't have a major impact on the industry -- that alone is worth scrapping the browser engine and rewriting from scratch.

I thought the mission of Mozilla was to ensure the web stays open. If their only lasting result in the end is to have produced the new standard systems programming language, that's an impressive feat.

But they'd also be a complete and utter failure.

99% of the time, some flash crap holds up my browser and all of FF freezes. Yet with Chrome, never happens.

That is the #1 feature that trumps everything for me, even though I think FF is superior to chrome in many ways including Firebug.

Plus they increased the timeout until it's recognised as crashed by about 10 times recently and it's absolutely awful now.

The long timeout is there so freaken' farmvile works. But the whole browser freezes.