[Nightly Update] Firefox 79.0 Comes with Hidden Secret “Experiments” Page

NOTE: This article is updated whenever some new and interesting features are introduced in Nightly builds of Mozilla Firefox web browser. So keep checking this page regularly. Nightly builds are testing versions of Mozilla Firefox browser which are under development and contain new features and improvements for testing and feedback purposes. These builds might contain bugs and issues. [Read More]

UPDATE 142:

The latest Nightly 79.0 build comes with a new hidden secret Experiments page which can be accessed using Firefox Options (about:preferences) page.

The page is not activated and enabled by default. Interested users can enable it manually by setting browser.preferences.experimental preference/flag to True using about:config page.

Once enabled, you can directly access it using about:preferences#experimental URL in address bar.

Following screenshot shows the new Experiments page in Firefox Nightly:

Mozilla_Firefox_Nightly_Experiments_Page.png

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At the moment very few options are available to change such as AVIF, CSS Masonry Layout, WebGPU.

More options will be added in future Nightly builds.

More Info: [Tip] Enable Hidden Secret Experiments Page in Mozilla Firefox

UPDATE 141:

The latest Nightly 73.0 build comes with a new UI option to customize default Zoom level for all websites in the browser. The new option has been added to Firefox Options (About:Preferences) page.

Zoom_Level_Customize_Option_Firefox_Preferences_Page.png

UPDATE 140:

The latest Nightly 73.0 build comes with a new hidden preference/flag which can be used to permanently enable and add Tab Manager button to Firefox toolbar. To enable this feature, set browser.tabs.tabmanager.enabled preference to True in about:config page. You’ll need to restart Firefox Nightly to apply changes. After restart, you’ll see the new drop-down arrow button on the tab bar to show a list of all running tabs.

Enable_Tab_Manager_Button_Mozilla_Firefox.png

More Info: [Tip] Enable Opera Style “Tab Manager Menu” in Mozilla Firefox Tab Bar

UPDATE 139:

The latest Nightly 73.0 build comes with a new about:profiling page for Firefox profiler settings. Currently the page is under development and will get lots of updates and changes in upcoming builds.

UPDATE 138:

The latest Nightly 72.0 build comes with new dedicated enable/disable toggle buttons to turn on/off installed extensions and themes quickly and easily in Add-ons Manager (about:addons).

Toggle_Button_Enable_Disable_Addons_Manager_Mozilla_Firefox.png

Thanks to our reader “Ehyan” for sharing this tip…

UPDATE 137:

The latest Nightly 71.0 build comes with brand new redesigned address bar which has been referred as “Megabar” by Mozilla. Initially it was called Quantumbar but now it has been renamed to Megabar.

Following screenshot shows the new Megabar in action:

Mozilla_Firefox_Megabar_Quantumbar.png

A hidden preference/flag browser.urlbar.megabar in about:config page can be used to enable/disable it. You’ll need to restart Firefox Nightly to take effects.

More Info: [Tip] Enable New Redesigned Address bar “Megabar” in Mozilla Firefox

In latest stable version of Firefox the preference is present with browser.urlbar.quantumbar label.

PS: The new Megabar of Firefox is quite similar to the new Reborn 3 address bar of Opera:

[Opera Tip] Enable or Disable New “Reborn 3” Dropdown Suggestions UI in Address bar

UPDATE 136:

The latest Nightly 70.0 build comes with brand new Firefox Nightly logo. Following image shows old and new logos:

Mozilla_Firefox_Browser_Nightly_Old_New_Logo.png

Apart from the updated logo, there are changes in color palette, typeface, etc as announced here.

Soon we’ll see new updated logo in Firefox stable release as well.

Thank to our reader “Onus” for the update…

UPDATE 135:

The latest Nightly 69.0 build doesn’t allow use of classic userChrome.css and userContent.css files by default. It has been done to speedup Firefox loading/startup time. Users who want to use these classic files for Firefox customization, will need to manually set toolkit.legacyUserProfileCustomizations.stylesheets preference to True in about:config page.

More Info:

[Fix] userChrome.css and userContent.css Codes Stopped Working After Firefox Upgrade

More info about these CSS files:

All About Mozilla Firefox Profile Folder and Configuration Files

UPDATE 134:

The latest Nightly 68.0 build allows users to change “View Page Source” option behavior. By default, when you right-click on a web page and select “View Page Source” option or press Ctrl+U hotkey, the page source opens in a new tab in the same window. This functionality was added to Firefox 42 version and since then all Firefox versions open web page source in new tab.

Mozilla team also added a new preference view_source.tab to about:config page in Firefox 42 version to modify this behavior. Users could set the preference to False to restore the previous behavior and open web page source in new window rather than new tab.

But Mozilla team removed the view_source.tab preference from Firefox 60 version and users could no longer change this behavior. Page sources always opened in new tabs.

Now Mozilla team has re-added the view_source.tab preference to about:config page in Nightly 68.0 builds which means now you can again decide whether Firefox should open web page source in a new tab or a new window.

More Info:

[Firefox Tip] Always Open “View Page Source” in a New Window Not Tab

UPDATE 133:

The latest Nightly 68.0 build comes with dark theme mode support for all About pages such as Add-ons Manager, Options, error pages, etc. So now if you enable dark mode in Firefox, all about pages will also use dark mode.

Mozilla_Firefox_Dark_Theme_Mode_Support.png

Dark mode support for about pages is not enabled by default. You can activate and enable it by setting browser.in-content.dark-mode preference to True on about:config page.

More Info: [Tip] Enable Dark Mode Everywhere in Mozilla Firefox

UPDATE 132:

The latest Nightly 68.0 build comes with new “Firefox Account” icon in toolbar. Mozilla team has added Google Chrome style user account icon in Firefox toolbar.

Following screenshot shows the new account icon in action:

User_Account_Profile_Icon_Mozilla_Firefox_Toolbar.png

When you click on the icon, it shows the signed in account ID and provides various options such as send tabs to device, manage account, change sync settings and sync now.

The icon can be removed easily by right-clicking on the icon and selecting “Remove from Toolbar” option.

More Info: [Tip] How to Remove Firefox Account (Sync) Icon from Toolbar

Thanks to our reader “Kay” for the update…

UPDATE 131:

The latest Nightly 67.0 build comes with redesigned Add-ons Manager (about:addons) page. The new UI (User Interface) is not enabled by default. You can activate and enable it by setting extensions.htmlaboutaddons.enabled preference to True on about:config page.

More Info: [Tip] Enable New Secret UI of Add-ons Manager in Mozilla Firefox

UPDATE 130:

The latest Nightly 67.0 build comes with Picture in Picture (PIP) mode. If you are watching a video on a webpage, you can right-click twice on the video and select “Picture in Picture” option from context menu. It’ll pop-out the video into a separate and always on top window.

Mozilla_Firefox_PIP_Picture_In_Picture_Mode.png

This feature is not enabled by default at the moment. You can enable this feature by setting the media.videocontrols.picture-in-picture.enabled preference to true on about:config page.

UPDATE 129:

The latest Nightly 67.0 build comes with redesigned “About:Config” page. The page can be accessed by typing about:config in address bar and press Enter key. It’s an advanced configuration page in Firefox which can be used to change functionality and enable/disable features.

Following screenshot shows new redesigned about:config page in latest Nightly build:

Redesigned_About_Config_Page_Mozilla_Firefox.png

[Tip] How to Restore Old About:Config Page in Mozilla Firefox

UPDATE 128:

The latest Nightly 66.0 build comes with support for keyboard shortcuts for installed extensions. If you open Add-ons Manager (about:addons) in Firefox, you’ll see a new button “Keyboard Shortcuts” as shown in following screenshot:

Manage_Keyboard_Shortcuts_Extensions_Mozilla_Firefox.png

Clicking the button opens a new page where you can manage keyboard shortcuts for all installed extensions. If an extension supports keyboard shortcuts, Firefox will show a textbox to enter or edit the keyboard shortcut. If an extension doesn’t support keyboard shortcuts, Firefox will show “There are no shortcuts for this extension” message.

UPDATE 127:

After updating UI of “about:performance” page as mentioned in previous update, now it’s turn of “about:addons” page. The latest Nightly 64.0 build comes with a redesigned “Add-ons Manager” page which can be accessed using about:addons URL in address bar or by selecting “Add-ons” option from main Firefox menu or using Ctrl+Shift+A hotkey.

Following screenshot shows the new UI of Add-ons Manager page:

New_Addons_Manager_UI_Mozilla_Firefox.png

According to Mozilla, this new UI of Add-ons Manager page is a small part of major re-design which will be introduced in Mozilla Firefox future version scheduled to release in 2019.

UPDATE 126:

The latest Nightly 64.0 build comes with a redesigned about:performance page as shown in following screenshot:

Mozilla_Firefox_New_About_Performance_Page.png

The old classic about:performance page can be restored by setting “dom.performance.enable_scheduler_timing” preference to False in about:config page.

More Info:

[Tip] How to Restore Classic “About:Performance” Page UI in Mozilla Firefox

UPDATE 125:

If you are using the latest Nightly 64.0 build in Windows 10, it’ll now show all web push notifications in Action Center (toast notifications). Recently Google Chrome also started showing native notifications in Windows 10 Action Center. (Read More)

Mozilla_Firefox_Native_Notifications_Windows_10_Action_Center_Toast.png

If you want to restore the old classic push notifications UI in Firefox Nightly builds, you can set the “alerts.useSystemBackend” preference to False in about:config page.

More Info:

[Tip] Enable/Disable Mozilla Firefox Notifications to Show in Windows 10 Action Center

UPDATE 124:

The latest Nightly 64.0 build comes with some new options in the context menu which appears when you right-click on a tab in tab bar. Now a new menu “Move Tab” has been added to the context menu which provides options to move a tab to start or end of the tab bar. It also contains an option to move tab to a new window. Previously we needed to drag-n-drop the tabs to move them.

Move_Close_Tabs_Mozilla_Firefox.png

Also “Close tabs to the right” and “Close other tabs” options have been moved to a new menu “Close Tab Options“.

UPDATE 123:

Mozilla has removed the “Never check for updates” option from the latest Nightly 63.0 build. Now there are only 2 options available in Firefox Preferences page: “Automatically install updates” and “Check for updates but let you choose to install them“.

Mozilla_Firefox_Automatic_Updates_Installation_Options.png

Now you can’t prevent Firefox from checking for new version updates which is a good thing in my opinion. We should always keep our web browser updated for better security and performance.

UPDATE 122:

The latest Nightly 63.0 build comes with a new option to block autoplay videos with sound on websites. By default, the option is selected to “Always ask” but you can change it to “Block autoplay” or “Allow autoplay“.

You can configure this new option using Firefox preferences/options page. It’s present under “Privacy & Security -> Permissions” section with the label “For websites that autoplay sound“.

You can also add exceptions to enable selected websites to autoplay videos and sound.

Block_Autoplay_Videos_With_Sound_Firefox.png

UPDATE 121:

The latest Nightly 63.0 build comes with support for Windows 10 dark mode feature. If you apply dark app mode in Windows 10, Firefox automatically switches to dark theme to respect Windows 10 dark mode settings.

Enable_Mozilla_Firefox_Dark_Theme.png

Check out following articles for more information:

Mozilla Firefox Joins Windows 10 Dark Mode Feature

[Fix] Disable Forced Dark Theme Mode in Mozilla Firefox in Windows 10

UPDATE 120:

The latest Nightly 62.0 build comes with a new preference which allows users to select multiple tabs. This feature is disabled by default and can be activated using the secret about:config page.

If you want to enable this feature, just set “browser.tabs.multiselect” preference to True in about:config page.

Now you can press and hold CTRL key and click on multiple tabs to select them. The selected tabs text will turn into bold which lets you know that the tab has been selected. Now right-click on tabs and you’ll get a new option “Close Selected Tabs“.

More Details: [Tip] Enable Multiple Tabs Selection Feature in Mozilla Firefox

Currently the work is under development and more options will be added in upcoming builds.

UPDATE 119:

The latest Nightly 61.0 build shows the downloaded files in “Highlights” section on New Tab page as shown in following screenshot:

Downloads_Highlights_New_Tab_Page_Mozilla_Firefox.png

You can dismiss or remove the item from history. You can also open the file or the folder containing the downloaded file. You can access all these options by clicking on the 3-dots menu which appears when you hover mouse cursor over the downloaded item.

If you don’t want Firefox to show downloads in Highlights section on New Tab page, you can uncheck the “Most Recent Download” option on Preferences -> Home page.

UPDATE 118:

The latest Nightly 61.0 build comes with a new preference which allows users to double-click on a tab to close it. This feature is disabled by default and can be activated using the secret about:config page.

If you want to enable this feature, just set “browser.tabs.closeTabByDblclick” preference to True in about:config page.

More Info: [Tip] Enable Double-Click to Close Tabs Feature in Mozilla Firefox

UPDATE 117:

The latest Nightly 61.0 build comes a new “Home” section in Options (about:preferences) page.

Firefox_Preferences_Home_Section.png

This new section allows users to choose what elements should be shown on homepage, new window and new tabs.

More Info: [Tip] Set a Blank Page as New Tab Page and Homepage in Mozilla Firefox

UPDATE 116:

The latest Nightly 59.0 build comes with a new feature called “Tab Warming“. This feature has been implemented to make the tab switching faster.

Currently the feature is disabled by default. Interested people can activate it by setting “browser.tabs.remote.warmup.enabled” preference to True in about:config page.

More Info: [Tip] How to Disable Tab Warming Feature in Mozilla Firefox

UPDATE 115:

The latest Nightly 59.0 build shows “Insecure Connection Icon” for non-HTTPS websites in the address bar.

Insecure_Connection_Icon_Mozilla_Firefox_Addressbar.png

Check out following article for details:

[Firefox Tip] Show / Hide Insecure Connection Icon in Address Bar

UPDATE 114:

The latest Nightly 59.0 build comes with a hidden secret Easter Egg which features a “Unicorn” game:

Mozilla_Firefox_Easter_Egg_Unicorn_Game.png

You can learn more about this Easter Egg at following link:

Hidden Secret Easter Egg Found in Firefox Nightly to Play “Unicorn” Game

UPDATE 113:

The latest Nightly 57.0 build comes with a new option in Preferences page to show/hide search box in toolbar. Open Firefox Options page, go to Search tab and enable “Add search bar in toolbar” option and it’ll immediately enable search box in toolbar:

Add_Search_Bar_Firefox_Toolbar.png

UPDATE 112:

The latest Nightly 57.0 build comes with a new option “Snippets” on new tab page. It shows updates from Mozilla, Internet culture and random meme. Snippets are shown in form of a horizontal bar at the bottom of the new tab page.

You can show/hide snippets using new tab page preferences:

Snippets_Firefox_New_Tab_Page.png

UPDATE 111:

Mozilla has replaced the previous “Recommended by Pocket” section on New Tab page with new “Highlights” section in the latest Nightly build 57.0 build. The new “Highlights” section displays recently visited web pages and bookmarked links. You can enable/disable the section using new tab page preferences.

PS: Mozilla has also removed search box from toolbar. You can re-add it using toolbar customize window.

[Firefox Tips] Restore Search Box on Toolbar and Remove Extra Spaces Around Address Bar

Highlights_New_Tab_Page_Mozilla_Firefox.png

Thanks to our reader “Kay” for the update…

UPDATE 110:

Mozilla has changed the Nightly icon on new tab page again in the latest Nightly 57.0 build. Also if you click on the gear icon on new tab page to customize settings, you’ll find a new option to show two rows on new tab page:

Show_Two_Rows_New_Tab_Page_Firefox.png

UPDATE 109:

The latest Nightly 57.0 build comes with a new Nightly icon on new tab page:

New_Firefox_Nightly_Icon_New_Tab_Page.png

Previously a Fox face was shown in its place:

Fox_Emoji_New_Tab_Page_Firefox.png

Thanks to our reader “TechKnow Geek” for the update…

UPDATE 108:

The latest Nightly 57.0 build comes with a new preference which allows users to always open bookmarks in new tabs.

Open_Bookmarks_Tabs_Mozilla_Firefox.png

Check out following tutorial for more details:

[Tip] How to Always Open Bookmarks in New Tabs in Mozilla Firefox

UPDATE 107:

The latest Nightly 57.0 build comes with a new tab loading animation. As soon as a page starts loading, a new indicator is shown on the tab:

Firefox_New_Tab_Loading_Animation.png

UPDATE 106:

In the latest Nightly 57.0 build, Mozilla has re-added the Fox face icon/emoji on the top-left corner of new tab page.

Mozilla_Firefox_Nightly_Fox_Icon.png

A new label “Nightly is all new. See what you can do!” has been added next to the icon. The Fox icon is not new, it was added in Nightly build 56.0 but was removed in later builds.

Check out more info about this icon:

[Firefox Tip] Restore Fox Face Icon (Getting Started Tour) on New Tab Page

UPDATE 105:

The latest Nightly 57.0 build comes with all legacy add-ons disabled by default. Now Firefox only supports WebExtensions.

The disabled legacy add-ons are displayed in a new section “Legacy Extensions” in Add-ons Manager page:

Mozilla_Firefox_Legacy_Extensions.png

If you want to enable support for legacy extensions again in Nightly, set the “extensions.legacy.enabled” preference to true in about:config page. Now all legacy extensions will start working again in Nightly.

UPDATE 104:

The latest Nightly 57.0 build comes with a new look of its Options (about:preferences) Page as shown in following screenshot:

New_Look_Mozilla_Firefox_Preferences.png

The new UI looks neat and modern. You can learn more about changes to Options page in following article:

Firefox Gets New Updated UI for Options (About:Preferences) Page

You can disable the new UI and restore old classic Preferences page using following tutorial:

[Firefox Tip] Restore Old Classic Options (About:Preferences) Page

UPDATE 103:

The latest Nightly 57.0 build comes with a brand new program icon which looks awesome and very pretty:

New_Firefox_Nightly_Icon.png

Following image shows both old and new Nightly icons:

Old_New_Firefox_Nightly_Icon.png

UPDATE 102:

The latest Nightly 57.0 build comes with a new redesigned theme which features square tabs and new icons set as shown in following screenshot:

New_Mozilla_Firefox_Photon_Theme.png

UPDATE 101:

In previous update we told you that Mozilla has enabled the activity stream feature on new tab page in Firefox Nightly build. Now in the latest Nightly 56.0 build, a new section called “Recommended by Pocket” has been added to the new tab page. This section shows top stories taken from Pocket service which is a part of Mozilla family.

Activity_Stream_New_Tab_Page_Mozilla_Firefox.png

You can disable this section by unchecking “Top Stories” option given in new tab page settings.

Check out following article for more info about this feature:

[Firefox Tip] Enable Hidden Secret Activity Stream on New Tab Page

NOTE: All previous updates about older Nightly builds are available here.

PS: If any of your favorite extensions is not working in a nightly build, you can follow instructions given in following topic:

How to Fix Broken Incompatible Extensions in Mozilla Firefox Newer Versions

Published in: Mozilla Firefox

About the author: Vishal Gupta (also known as VG) has been awarded with Microsoft MVP (Most Valuable Professional) award. He holds Masters degree in Computer Applications (MCA). He has written several tech articles for popular newspapers and magazines and has also appeared in tech shows on various TV channels.

Comments

NOTE: Older comments have been removed to reduce database overhead.

  1. Nightly (2017-09-02) sports an ‘Accessibility Features Enabled’ icon on the tab bar:

    imgur.com/a/AsvoI

    to disable the icon, toggle the about:config setting ‘accessibility.indicator.enabled’ to false.

  2. @VG
    Whenever I open Nightly:

    imgur.com/a/5EPNw

    Brings me to a page without content though!:

    imgur.com/a/q7QDI

  3. Those who miss the previous “Share” feature, removed in Nightly 57, can install a ‘backported’ version:

    addons.mozilla.org/en-US/firefox/addon/share-backported/

  4. I use Firefox for work; came in this morning and could not find my bookmark folders. Blew almost an hour – while trying to finish a presentation. Doing a major upgrade in the middle of the work week is just plain rude. Screwing around with bookmarks, essentially a personal feature, is way, way wrong. Bye bye Mozzilla – back to IE.

  5. Nightly 59.0a1 noteworthy:
    ‘Screenshots’ will save to the Clipboard to paste, for example, into Paint.

    An ‘Easter Egg’ has showed up in Nightly at some point:
    If you ’empty’ the ‘Customize’ Page by putting all items on the Toolbar temporarily, a Mozilla Unicorn box will show up at the bottom next to the ‘Density’ Box;
    Click on it to invoke a ‘Pong’ game controlling the upper ‘Flexible Space’ paddle with your left and right arrow keys! 😉

  6. Nice tip on the “Tab Warming” feature! Thanks for that! 🙂
    Seems to work on any link, bookmarks as well.

  7. When you click on the ‘Settings Sprocket’ on the New Tab page, it kicks you over to the Home section on the Options page!
    Kinda weird!

  8. I think disabling automatic updates rots ass. I use Sandboxie, Hostsman and Winpatrol, and haven’t had a virus in years. I spoke with a Win10 user who can’t disable updates, and he says they keep breaking his system. I want a reason to update before I do. How high-handed! How like Chrome! If I wanted to use Chrome, I’d use that! If Goolagle want’s to install spyware, or take money for allowing the install of ransomware, Chrome users couldn’t stop it. This is not yet a deal-breaker. Next major version #?

  9. Is there a way to go back to the old tab context menu?
    Having “close tabs to the right” in a submenu is a deal breaker for me.

  10. ^^ Currently no way. Wait for some time. There will be more changes to the context menu and options.

  11. In Nightly 69, to disable ‘Recommended Themes & Extensions’ in the Add-ons page, toggle ‘extensions.htmlaboutaddons.recommendations.enabled’ to False in about:config.

  12. The latest build for Firefox Nightly features the updated logo with aesthetics as per blog.mozilla.org/opendesign/firefox-the-evolution-of-a-brand/

  13. Initial HDR support added.

    Loading youtube.com/watch?v=mkggXE5e2yk will now show HDR streams (though displaying in HDR can be hit and miss)

    More details here: mozillagfx.wordpress.com/2019/08/19/moz-gfx-newsletter-47/

  14. Enable/disable toggles now back to Extensions and Themes section of about:addons as of the latest nightly build of posting this comment. It will now be easier to enable/disable an add-on similar to the one before the about:addons redesign.

  15. In order for the Default Zoom option to work be sure to set “browser.zoom.siteSpecific” to “true” in “about:config”.

  16. Entering a search keyword in a non-private window will now give the option to open it in a new private window.

    i.imgur.com/x7bLqRJ.png

    Personal note: The option doesn’t seem to appear if Firefox offers other urls as suggestions based from history or bookmarks from the currently typed keyword.

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