Mozilla/5.0 (Windows NT 6.1; rv:2.0b5pre) Gecko/20100827 Minefield/4.0b5pre (VM) When using Panorama and tab previews in Aero Peek odd things can happen. When you hover over the thumbnails in tab preview, you can get tabs shown and added to a tab group that didn't originally have them. Steps: 1. Open Fx and open, say, five tabs in a window. 2. Click on the Panorama button and drag one of the tabs from its group out onto its own 3. Click on the latter tab group. - At this point you should see a single window with a single tab on your desktop 4. Hover over the Fx icon in the taskbar, and assuming you have Aero Peek enabled, you will see a list of all the tabs currently open in your browser sersion. 5. Hover over the thumbnails. You will notice that as you hover, say left to right, those tabs will get added to the single-window/single-tab view you had in step 3. If you select the last thumbnail you'll get a window with all your tabs. Expected: I should only see the one tab because I had dragged it onto its own group. Actual: You get all the tabs. Adding a new tab will make all other tabs disappear, except for the one in its own group. Clicking on any of the other tabs will make the single tab disappear.

Juan, is this still a verified problem?

This is a verifiable valid problem. Today I tried with 4.0b8pre (10/12), and I still see this problem.

This is a system state-loss issue, so adding it to b8.

Anant, is this something you can take on?

We expect bug 605338 to land before FF4.0, and bug 586155 after FF4.0, so punting this to the future.

Removing blocking flag per comment #6.

Renominating for blocking as comment 6 no longer applies; Peak will probably be on by default. Moving to our current workload and reassigning as Anant is swamped.

Not going to block on this because we're disabling aero peek for FF4.

As Aero Peek is disabled by default in fx4, we will punt on this.

Panorama has been removed from Firefox 45, currently in Beta and scheduled for release on March 7th. As such, I'm closing all existing Panorama bugs. If you are still using Panorama, you will see a deprecation message in Firefox 44, and when 45 is released your tab group data will be migrated to bookmarks, with a folder for each group. There are also a few addons offering similar functionality. See https://support.mozilla.org/en-US/kb/tab-groups-removal for more info. We're removing Panorama because it has extremely low usage (about 0.01% of users), and has a large number of bugs and usability issues. The cost of fixing all those issues is far too high to justify, and so we'll instead be focusing our time and energy on improving other parts of Firefox.