Firefox 24: Find out what is new

Martin Brinkmann
Sep 17, 2013
Updated • Aug 10, 2015

Mozilla will push out an update of the popular Firefox web browser later today that brings the stable channel to version 24. As always, it is available early on the official Mozilla ftp server and on third party download portals.

The other channels, beta, aurora and nightly, will also receive an update in the coming days raising their version count by 1 as well.

Firefox users who have automatic updates configured in the browser - it is the default setting - will receive notifications of the update later today so that they can update to the new version.

Users who have disabled the feature need to download it manually instead, either from the ftp server directly or from Mozilla's official website to install it manually in the browser instead.

Firefox 24 What’s New

firefox 24

The final release notes have not been published yet. Mozilla does however publish beta release notes which we can use to find out what is new in the latest version of Firefox.

We are also using other official sources, information for developers for example, in this overview to provide you with detailed information about the changes in Firefox 24.

Close Tabs to the right

firefox close tabs to the right

Mozilla has added a new menu item to the context menu when you right-click a tab in the browser's tab bar.  Here you find the usual options to pin a tab, close tabs, undo close, and the new close tab to the right item.

It closes all tabs to the right of the selected tab on selection. The feature can be quite useful in situations where you have opened - some - tabs for a short period of time. This may reflect your browsing habit on sites such as Reddit for example, especially the picture section there.

Instead of closing all tabs manually, you simply invoke the close tabs to the right action and be done with that with two clicks.

Social chat tear-off option

social chat

If you are using Firefox's social feature you may have noticed that all of the information it makes available are attached to the browser window in a fixed fashion. That's not always what you want, especially when it comes to chat.

Starting in Firefox 24, it is possible to drag and drop chat windows from the main browser into their own window so that you can use them independently from it.

To do so, hold down the left-mouse button on the chat interface and drag & drop it to another location before you release the mouse button. It is alternatively possible to click on the small arrow next to the minimize and close icons in the window's title to do the same thing.

You can then control the window just like any other, resize it for instance if you want or move it around.

Java changes

java firefox 24

As mentioned earlier, Java is considered insecure by Mozilla. That's why the organization made the decision to remove the "always activate" option from the plugin.

As you may know, plugins can have three states in Firefox:

  • Always activate means it is enabled on all websites by default.
  • Never activate means it is disabled.
  • Ask to activate means that click to play is used to turn on the plugin on a per-page basis.

Java can only be set to the never activate or ask to activate state from Firefox 24 on.

Note that Mozilla will apply the change to all plugins but the latest Flash version from Firefox 26 onwards.

Mp3, AAC and H.264 support

I was not able to test this so take this with a grain of salt. Linux users may play Mp3, AAC and H.264 contents in the web browser without plugins from Firefox 24 on.

The preference gstreamer.enabled determines whether the feature is enabled or not. To change it do the following:

  1. Type about:config into the browser's address bar and hit enter.
  2. Confirm that you will be careful if this is your first time.
  3. Search for gstreamer.enabled
  4. Make sure it is set to to true (which means enabled).

Other changes

  • Support for new scrollbar style in Mac OS X 10.7 and newer

Developer changes

Additional information about these changes are available in the source links section below.

  • The two values -moz-zoom-in and -moz-zoom-out of the cursor property have been unprefixed to zoom-in and zoom-out.
  • The <track>  element has been implemented behind the media.webvtt.enabled property.
  • Arrow functions are no longer automatically in strict mode unless explicitly requested with "use strict".
  • The String.prototype.repeat JS method has been implemented.
  • Support the Range(), Text(), Comment(), DocumentFragment() constructor has been added.
  • The FocusEvent interface has been implemented.
  • Support for the ChildNode.remove() method has been added.
  • TextTrack, TextTrackCue, TextTrackList and TextTrackCueList have been implemented.
  • Navigator.getGamepads has been implemented but set to false by default.
  • mozLoadFrom() of HTMLMediaElement has been removed.
  • HTMLCanvasElement.getContext() can now take the webg1 value on Firefox desktop.
  • The Network Inspector can now filter by content type, e.g. CSS, image).
  • JavaScript can now be temporarily disabled or enabled in the Devtools options panel.
  • Browser Console implemented which replaces the Error Console.
  • Support for W3C touch events has been disabled.

Security updates / fixes

MFSA 2013-92 GC hazard with default compartments and frame chain restoration
MFSA 2013-91 User-defined properties on DOM proxies get the wrong "this" object
MFSA 2013-90 corruption involving scrolling
MFSA 2013-89 Buffer overflow with multi-column, lists, and floats
MFSA 2013-88 compartment mismatch re-attaching XBL-backed nodes
MFSA 2013-87 Shared object library loading from writable location
MFSA 2013-86 WebGL Information disclosure through OS X NVIDIA graphic drivers
MFSA 2013-85 Uninitialized data in IonMonkey
MFSA 2013-84 Same-origin bypass through symbolic links
MFSA 2013-83 Mozilla Updater does not lock MAR file after signature verification
MFSA 2013-82 Calling scope for new Javascript objects can lead to memory corruption
MFSA 2013-81 Use-after-free with select element
MFSA 2013-80 NativeKey continues handling key messages after widget is destroyed
MFSA 2013-79 Use-after-free in Animation Manager during stylesheet cloning
MFSA 2013-78 Integer overflow in ANGLE library
MFSA 2013-77 Improper state in HTML5 Tree Builder with templates
MFSA 2013-76 Miscellaneous memory safety hazards (rv:24.0 / rv:17.0.9)

Additional information / sources

The following links point to official sources that provide you with additional information about the release. Note that some may not have been updated yet.

  1. Add-on Compatibility for Firefox 24
  2. Firefox 24 for Developers
  3. Firefox 24 release notes
  4. Security advisories for Firefox 24

Tutorials & Tips

Previous Post: «
Next Post: «


  1. tinwheeler said on September 18, 2013 at 8:21 pm

    Martin, You mentioned that the Australis non-customizations are coming in version 25. I am running 25 beta 1 and can still customize the plug-ins, add-ons, etc.. Are the changes only coming in 25 final?

    1. Martin Brinkmann said on September 18, 2013 at 8:36 pm

      Mozilla has not confirmed anything yet. It is possible that Australis will get delayed further, but we do not know for sure until Mozilla makes an official statement.

  2. blah blah blacksheep said on September 18, 2013 at 8:02 pm

    I kept getting random browser crashes in FF 23. The whole browser would just randomly go down, usually if I had it open for about 30 minutes. This was regardless of how many or how few tabs I had open. I’m hoping FF 24 fixed whatever was causing the issue. Never happened in FF 22.

  3. Anonymous said on September 18, 2013 at 7:33 am

    I really appreciate that Mozilla sped up the tabs page,
    I was complaining about how slow it was just a few days ago.

  4. Anon said on September 18, 2013 at 5:57 am

    I just upgraded to the latest version of Firefox, which is 24. I did not know it was just released today. I would have waited for a bit, had I had known that.

    The “Instagram problem” that was posted above…I believe that’s what I’m experiencing. When I click on an Instagram pic to enlarge it, it doesn’t let me. This was not a problem for me before I upgraded Firefox.

    Firefox 24 is also crashing a lot. Every time I sign into Gmail, it crashes. Same with Instagram, and who knows what else. Very frustrating, since everything was working fine before.

    Do you guys think this is something that will naturally go away? If not, what should I do? I’ve rebooted, and I know I don’t have any viruses. Also, all my Add-ons are up to date, except for Java, which is disabled anyway. And nothing’s changed in that regard. I wasn’t getting crashes before.

    I was wondering should I update Java since Firefox disables it anyway? Should I not even bother?

    1. tinwheeler said on September 18, 2013 at 8:31 pm

      Anon, You might try going into your AppData folder and saving your profile and profile manager folder to your desktop, then load FF 24 and add your profile and profile manager folders back in and then reboot. Once in a while if you add a new version on top of a previous one this happens.

    2. blah blah blacksheep said on September 18, 2013 at 8:10 pm

      I would update Java if you have it installed simply to have the most current (IE: securely patched) version on your computer, regardless of whether Firefox uses it or not.

      But, other than that, updating Java shouldn’t impact FF if it’s deactivated in the add-ons.

      I sort of wonder if FF / Mozilla is leveraging some technology that takes advantage of newere hardware (IE: stuff built in past 5 years), but is ostracizing older tech. I’m on an old Celeron (P4-era) with 1gb ram and WinXP. FF 23 started randomly crashing on me for no apparent reason. Not sure if FF 24 is going to continue the issue. But, if the browser was working up through v 22, and now it just randomly crashes on v 23 (hasn’t crashed on v 24 … yet) … it means something changed. My computer hasn’t updated. My hardware hasn’t changed. Only thing that changed was FF.

      1. Martin Brinkmann said on September 18, 2013 at 8:46 pm

        You are right, updating Java should not impact Firefox at all if it is disabled in the browser, or if you have disabled Java from integrating itself in browsers (I prefer the latter as I do not use any Java contents on the web).

      2. Martin Brinkmann said on September 18, 2013 at 8:40 pm

        I can’t think of any particular feature that was introduced in Fx22 that would degrade performance on older machines. Are the crashes happening on specific pages or when you are accessing certain types of contents, e.g. Flash? It could be an updated plugin and not Firefox directly.

  5. Anonymous said on September 17, 2013 at 10:03 pm

    I am still waiting for a viable sync option.
    The current one is a nightmare. Opera has just a password, same with Chrome. Firefox… aarghh…

  6. Betty A. Gunther said on September 17, 2013 at 8:07 pm

    I just downloaded Version 24 and the problem is solved.

  7. Betty A. Gunther said on September 17, 2013 at 7:57 pm

    For the past few days I have not been able to see or use facebook through Firefox. I simply get a blank screen when I click on a link to Firefox. I can see Facebook just fine using Internet Explorer. My ISP tells me lots of people are having this problem. Do you have any idea how to fix this? As far as I know I am completely up to date on Firefox — am on version 23.0.1. I update my Firefox whenever told to do so.

  8. Karl J. Gephart said on September 17, 2013 at 4:40 pm

    Martin, I’m guessing the big non-customization Australis changes still aren’t coming until version 25?

    1. Martin Brinkmann said on September 17, 2013 at 5:25 pm

      Yes that is correct.

      1. Karl J. Gephart said on September 17, 2013 at 5:33 pm


  9. Ficho said on September 17, 2013 at 4:20 pm

    Can I install Firefox 24 ESR over existing “normal” Firefox ?

    1. Martin Brinkmann said on September 17, 2013 at 4:27 pm

      It is not recommended. The safest way is to install Firefox ESR separately, and migrate the existing profile that you have over to it. If there is enough interest, I may write about other options that you have.

      1. lookmann said on September 17, 2013 at 5:51 pm

        Hi Martin,
        What is the difference between normal and ESR versions?

      2. Martin Brinkmann said on September 17, 2013 at 6:10 pm

        ESR versions are on a 42 week cycle instead of the six week cycle of stable. While they still get security updates just like the stable version of Firefox, they do not get other features directly. So, australis which may land in Firefox 25 Stable won’t reach ESR until Firefox 32 ESR.

  10. Tuman said on September 17, 2013 at 3:42 pm

    FileHippo uploads the latest final versions of Firefox before Mozilla updates the official Firefox page with the new version.

  11. Marcel said on September 17, 2013 at 3:15 pm

    Thanks Martin for your newsletter.

    Firefox 24.0esr is also available:

  12. lookmann said on September 17, 2013 at 3:09 pm

    Hi Martin,

    ‘Mp3, AAC and H.264 support
    Linux users may pay Mp3, AAC and H.264 contents in the web browser without plugins from Firefox 24 on.’
    You mean ,
    Linux users may play Mp3, AAC and H.264 contents in the web browser without plugins from Firefox 24 onwards.

  13. Anonymous said on September 17, 2013 at 3:05 pm

    “Linux users may pay Mp3, AAC and H.264 contents …”
    It should be play.
    (don’t bother posting this comment)

  14. David said on September 17, 2013 at 12:40 pm

    Seems like the Instagram bug is not fixed yet. What, it’s been like a month? :)

    1. Anonymous said on September 27, 2013 at 3:31 pm

      You think it’s so easy? Why don’t you magically fix it then? Remember, it’s an absolutely free program – you get lots for nothing, get over the tiny stupid bug, people are working on it…

Leave a Reply

Check the box to consent to your data being stored in line with the guidelines set out in our privacy policy

We love comments and welcome thoughtful and civilized discussion. Rudeness and personal attacks will not be tolerated. Please stay on-topic.
Please note that your comment may not appear immediately after you post it.