Mozilla Firefox 99 Is Now Available for Download with GTK Overlay Scrollbars

Firefox 99

Mozilla’s Firefox 99 open-source and cross-platform web browser is now available for download ahead of its official launch on April 5th, 2022.

Firefox 99 comes with good news for Linux users as this release brings GTK overlay scrollbars for a more modern look. This means that the scrollbars will now look thinner by default and appear bigger to allow you to manually drag them with the mouse cursor when you hover over them.

They also disappear after a second if no movement is detected. However, GTK overlay scrollbars are not yet enabled by default so you’ll have to go to the Advanced Settings page by typing about:config in the address bar, searching for the widget.gtk.overlay-scrollbars.enabled option, and setting it to true by double-clicking it.

This release also strengthens the Linux sandbox by restricting access to the X Window System (X11) for processes exposed to the web content. Users who use the Firefox Snap should be happy about this new security feature.

Also for Linux systems, Firefox 99 adds initial support for the Web MIDI API, which requires a site-specific add-on to enable it on your web page. “Initial” means that some limitations are present, such as the fact that device hot-plug detection is currently missing in this release, though it should work on most web pages.

Other than that, Firefox 99 appears to let users search for text with or without diacritics in the PDF viewer, as well as to toggle the ‘Narrate’ feature in the ReaderMode by pressing the “n” keyboard shortcut.

If you want to update your Firefox installation to version 99, you can download the binaries for 64-bit or 32-bit systems right now from Mozilla’s FTP server. But, if you have Firefox installed from the software repositories of your GNU/Linux distribution, I recommend waiting until the new version arrives there later this week.

Meanwhile, Mozilla is asking for the community’s help to test drive the Firefox 100 release, due out on May 3rd, 2022, for website compatibility with the three-digit version number.

You can do that by enabling the new Firefox 100 User-Agent String option in the Experimental section of the Settings page accessible via about:preferences#experimental and report issues at

Update 05/04/22: Mozilla officially released Firefox 99 today, April 5th, 2022, and also added the fact that the new version of their open-source web browser adds support for credit card autofill and capture in Germany and France.

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