Firefox has been improving its developer tools over the last few releases. The latest version 11 takes us into some new territory - 3D.
The new "tilt" feature lets you view a 3D representation of the DOM. The depth of nesting of a page element is mapped to its depth in a 3D view. So. for example. a button nested in a set of divs would stand out higher than a button in the body of the page. Once you have the 3D page on the screen you can rotate it and zoom to see anything that takes your interest.You can also select any area and see the tag list that creates it just as you can in the standard 2D representation.
This is great but I doubt it really will help anyone understand the page or find a bug. In fact even the 2D view isn't quite as useful as the Firebug inspection facility. However, a lot of time has already been spent viewing all sorts of websites and generally have a good time zooming and panning. It is a really great demonstration of what you can do with WebGL. Perhaps this should be the way all websites are viewed all of the time?
You can also watch the video presentation which shows the 3D view in action:
We also have a new style editor which is very useful. It's an upgrade to the style editor in previous versions of Firefox which you can use to change the CSS of the current page. The big new feature is that instead of showing you a summary of styles and properties extracted from the page it now shows you the actual style sheet used. This means that you can experiment with changes until you get the page as you want it or as it should be and then you can save the style sheet locally. This should really save time when fine tuning or debugging.
As well as developer tools the new version also includes SPDY (Google's go-faster version of HTTP). The idea is that if you encounter a site that offers SPDY you can take advantage of it or use HTTP if you don't want to be experimental. The feature has to be explicitly turned on.
The synchronization service has also been extended to include add-ons and you can now import user data from Chrome. Of course there have also been security and bug fixes, but oddly they didn't have to rush to patch a problem found in the recent Pwn2Own contest. It seems that this was already known about and fixed before the contest.