The Firefox development team has finally resolved what was probably the longest outstanding bug for the browser: full page zoom. Up until now Firefox has only been capable of increasing and decreasing the size of text to simulate zooming, but now it handles images as well! The funny part is that it only took 8-years for this bug to get fixed. :)
This is something that the Opera browser has had ever since I can remember, and it is something I’ve always longed for in Firefox. Heck, even Internet Explorer 7 has some sort of zoom capabilities that also scales images, but the results are typically not the best.
To get it in Firefox 3 you’ll need to be using the latest nightly build, along with this extension. The extension is just a temporary fix that lets you add buttons to the navigation bar for zooming, and without it there is no way to take advantage of the new zoom capabilities. Eventually the developers will get the feature integrated with the browser, but the extension is the best way to test it out for those that want to see what it is like.
Source: Mozilla Links