By Craig Buckler

What’s New in Firefox 20

By Craig Buckler

Version numbers may be meaningless but Firefox 20 marks a milestone for Mozilla’s flagship browser. The new release appeared on April 2 exactly six weeks after version 19. If you don’t have it, open Help > About Firefox or download the browser from

Firefox 20 has a surprising number of new features — let’s look at the best…

Developer Tool Updates

Firefox has received an incredible number of tools within the past few releases. The Developer menu has been reorganized to order them more effectively and a new Toggle Tools option provides quick access to the Web Console. The Console can also be viewed within its own panel as well as docked.

A new JavaScript Profiler had been promised for version 20 but the feature has been delayed for a later release.

New Download Manager

If I recall correctly, this is the first major update to the Download Manager since it appeared in Phoenix back in 2002. The dedicated panel has been replaced by a drop-down list accessed by a new toolbar icon which highlights the time remaining:

Firefox download manager

It’s a nice touch. Previous downloads are still logged in bookmarks and history panel.

getUserMedia Support

Firefox now provides the getUserMedia HTML5 API which has been available in Chrome and Opera for several months. With the user’s permission, you can capture audio and video from a microphone or camera. Opera’s Photo Booth provides an excellent demonstration of the technology.

canvas Blend Modes

When you draw on a canvas element any existing pixels are normally replaced. However, the new globalCompositeOperation property permits Photoshop-like overlay effects including multiply, screen, darken, lighten, color-dodge, color-burn and difference. Refer to this Mozilla article for more information.

Audio and Video playbackRate Support

Have you ever wanted to watch a tedious movie at double-speed? The playbackRate property permits just that (apologies for the inline code):

<video id="v" src="video.webm" controls autoplay></video>
<a href="#" onclick="document.getElementById("v").playbackRate=2;return false;">fast foward</a>

View a demonstration movie…

Improved Private Browsing

Private browsing prevents Firefox updating your history, caching pages, saving passwords and storing cookies.

While it’s been available for some time, clicking “Start Private Browsing” from the menu would close your current window and start a new session. From version 20, Firefox permits you to have any number of private and non-private windows open at a time.

Better Plugin Stability

Browser stability is largely irrelevant if your plugins cause chaos. Fortunately, the new version of Firefox detects hanging plugins and allows you to close them without restarting the browser. I doubt it will end plugin problems but it’s a step in the right direction.

Want More?

Firefox developers had a busy six weeks…

  • CSS and JavaScript now load with a higher priority than images to improve response times.
  • various ECMAScript 6 additions
  • performance improvements
  • a dozen security fixes.

I’m not sure how long Mozilla can keep up the pace of development, but other vendors should take note (seriously Google, could you only manage a spell checker in Chrome 26?!)

  • Dave

    Nice features overall but why oh why have they not sorted out the background in pop-up image windows. It used to be white and is now a black/very dark grey. Renders the use of transparent images as almost useless. :)


    • David

      That can be fixed, Dave. Get the Old Default Image Style Add-On. It fixes all of that.

  • Now that the Private Browsing experience has been refined, I may begin using FF a bit more in my day to day development processes, but now that I am a bit more used to working with Chrome’s development tools, it may be too little too late for FF, at least for this developer.

    It’s also exciting to see they will be supporting threading with the Servo rendering engine update, but that is still a year+ down the line. I think FF should have focused more on these fundamental issues much sooner than they did, they will be hard-pressed to catch up with the WebKit/Blink browsers now they have to focus development resources on features already available in other browsers.

    • I’ve always seen a pattern of complacency in companies with browsers: :Google did to Mozilla what Mozilla did to Microsoft, what Microsoft did to Netscape.

  • One thing I don’t like about ff20 is how Mozilla changed the inspection tool. When I drag the CSS view up on the right side, it drags the DOM view up across the width of the whole screen. They used to be independent of each other.

  • Jamshid

    They should be kidding, everytime I start FF it has new updates and very important security fixes :)))
    Thats way, I already switched to Chrome

    • dudezilla

      I see your logic (if indeed we may call it that) from moving away from a browser which in your own words is updated every time you start it, with very important security fixes…….and this prompted you to move to another browser. whew!
      Hopefully that other browser rarely updates and ignores the very important security fixes just so you can remain a faithful user.

      • DJ

        Not to mention that if FF updates “everytime” [sic] you start it you must not use it very often, in which case it doesn’t really matter which browser you’re using because it’s not evidently a ‘tool’ for you.

        I guess your memory could be failing you worse than FF?

  • i using FF17, when my FF17 start up, in a few second later my FF17 crash or suddenly not responding for 3 or 5 seconds. i dont know what happen, but i hope FF20 does not happen something like that

  • Inexu

    New DOM-inspector is big failure I ever seen in FF, because now it completely unhandy and unusable.
    Separated CSS-inspector, element layout view and HTML-code was greatest feature of the FF.

    • Harry

      Tottaly agree. Now it’s like, Chrome, you have to change the panel to see the box model, when it was possible in ffox 19 to view the style rules AND the box model at the same time. Also the style rules where displayed in a right pane and you could see the rules as much height your window had. Now it’s just like chrome, compacted with everything. It seems they tried to look like chrome. FAIL.

  • fs



  • The Inspector is a HUGE step backwards to be almost unusable. This was about the only reason I’m still using FF over Chrome. Some usability testing before letting deveopers fire off in random directions would be useful. Plus a good deal of “if it ain’t broke don’t fix it”. Specifically:
    + The CSS display was conveniently in the right-hand column – given the prevalence of wide-screen monitors this placed it in often dead space making it very usable.
    + The HTML view in the inspector previously had to be selected – given how much of the screen it took up I only enabled it when needed, which wasn’t very often. With the CSS view visible and the HTML view off I could easily find the CSS definitions and see the whole web page. Not any more!
    + Previously – hitting the escape key got rid of the inspector. Now I’ve got to move the mouse around and hit a little ‘X’

    Big BIG step backwards guys!

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