A tab preview is now displayed when hovering the mouse over background tabs

[Uffe]

This is the most annoying thing and unnecessary gadjet ever, who came up with this and please let the users that don't want it to have the possibillity to turn it of. For the moment I think it's almost ruin the surf experience.

[Agentvirtuel]

Hello

https://forums.mozillazine.org/viewtopic.php?t=3125486 in addition
For information purposes https://connect.mozilla.org/t5/discussions/tab-previews-are-annoying/m-p/72965/highlight/true#M27933

[ThePillenwerfer]

Type <code>about:config</code> into the search/URL bar.

That will bring up a warning which you'll have to acknowledge.

On the next screen there's a search box at the top. Type or paste browser.tabs.hoverPreview.enabled. That will then appear below with the word true next to it. Double-click true and it will change to false.