Showing a tab preview on hovering a tab is not a standard feature AFAIK.

Did you still try Save mode to rule out any extensions?

• https://support.mozilla.org/kb/Safe+Mode

Well, as strange as this is, it's gone now. I took your suggestion and started FF in safe mode and sure enough, it was gone. So, I restarted back into normal mode and then went to my extensions and decided to just disable them one at a time (I only have about eight extensions) and the after the very first one I disabled (FVD Suite, which I didn't think would have anything to do with it) the problem was gone. I then re-enabled that extension to see if it would reappear, but it did not, and the problem has not yet returned. I find this very strange, but I'm glad it's gone.

Thanks for the help.

Showing tab previews must be some sort of semi-hidden, accidental feature of Firefox 11. Because I had the same problem after updating.

It was remarkably annoying; whenever I hovered over a tab to do anything (close a tab, move a tab, etc.) the little preview would pop up, covering the tab, preventing me from doing anything with it. So I had to be really fast and sneaky with my mouse whenever I wanted to close or move a tab!

Anyway, I fixed it in a similar fashion to rc54, except I didn't disable a single add-on, which leads me to believe it's an issue with Firefox 11 that apparently only a handful of people have experienced.

All I did was restart Firefox in safe mode. Then I restarted Firefox again in normal full-mode again. I didn't change a thing, and the tab previews went away for good; problem solved.

There is a preview when i move the mouse between tabs , a pop up window, because of that i was unable to make changes immediately, so kindly solve this.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes