Tab previews allow you to hover over open tabs in the Firefox web browser to get a preview of the page’s content. Mozilla added the functionality into Firefox Nightly this week. Reason enough to take a look at the feature.
Tab Previews are only available in Firefox Nightly at the time of writing. The feature is disabled by default, but you may enable it.
This is done by setting the preference browser.tabs.cardPreview.enabled to true on about:config. A restart of the Firefox web browser completes the process.
Tip: you may set this feature to off in Firefox Stable later on to turn off tab previews. This restores Firefox’s display of the page title and URL then when you hover over a tab.
How Tab Previews work in Firefox
Hover over any open tab in Firefox and you see a thumbnail of the page after 1 second. The snapshot displays a screenshot of the top of the page. In other words, it ignores the actual position on the page.
It may look cut off as well, as you can see on the screenshot above. Still, hover over any tab and you do get a preview of the page.
Tab previews is a handy feature at times, especially if you have multiple tabs with the same title open. Think ten eBay auctions that have similar titles.
The 1 second delay is set by Mozilla. There is a preference that supposedly changes it, but it does not seem work right now. Check browser.tabs.cardPreview.delayMs on about:config to change the delay.
Comparison to Google Chrome
Firefox is not the only web browser that introduced support for tab previews recently. Google’s Chrome browser displays tab previews as well now in the Stable version.
Hover over any tab in Chrome and you get a screenshot preview of the tab. Google displays the same information as Firefox plus a tab’s memory usage.
There is one difference though. Firefox displays a screenshot of the top of the webpage all the time. Google Chrome, however, displays a screenshot of the actual position on the webpage.
It is possible that Firefox’s tab previews feature will also support this in the future. It is in development and it may change in the future though.
Closing Words
Not every browser user likes tab previews. It should be easy enough to turn these off in Firefox once they land in stable.
Now You: tab previews, yay or nay?