How to enable Tab Previews in Firefox

[harlan4096]

Mozilla released Firefox 123 a few days ago, and it comes with a new feature. The browser now supports Tab Previews, but you can't access it directly from the Settings.

The feature is quite similar to Tab Preview that is available in Google Chrome, Microsoft Edge, Vivaldi, Opera, and Brave Browser. When you hover the mouse over a tab, the browser displays a thumbnail of the web page. This can be useful if you want to view a tab's contents without actually switching between tabs.

Mozilla introduced the feature in the nightly version of Firefox earlier this month, before adding support for it in the stable version. Though Tab Previews are available in the latest version of Firefox, the feature is not enabled by default, likely because some bugs are being sorted out. There is no option that you can toggle from the browser's settings. Instead, you will need to make a change in the advanced configuration. Here's how you can do it.

How to enable Tab Previews in Firefox



1. Open about:config.
2. Click on Accept the Risk and Continue.



3. Paste the following text in the search bar.

browser.tabs.cardPreview.enabled

4. The flag is set to false by default.
5. Double-click on it to change it to true.



Note: browser.tabs.cardPreview.showThumbnails must also be set to true.

That's it. You don't even have to restart the browser after making the changes. Time to test if it works. Open a couple of tabs, and mouse over them, and Firefox will display the Tab Preview. It is worth mentioning that the feature only works with active tabs, i.e. tabs that are currently loaded. So tabs that are unloaded (upon browser restart) or those that have been snoozed by extensions like Auto Tab Discard will not display a Tab Preview, you will need to click on them to make them active.

Now, if you feel that the Tab Previews are displayed slowly, there is another setting that you can change. Look for the following setting:

browser.tabs.cardPreview.delayMs

 

It is set to 1000ms (1 second) by default, so the Tab Previews are displayed 1 second after you move the cursor over a tab. Set the value to 500ms or lower to reduce the delay. You can set it to 200ms to make the previews appear instantly.
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