Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.2a1pre) Gecko/20090722 Minefield/3.6a1pre Pressing Shift+Ctrl+Tab doesn't limit the shown thumbnails to the same amount of tabs as when pressing Ctrl+Tab. Instead the All Tabs panel is opened. Moving forward and backward in the tab list should behave identically.

This is intentional, per <https://wiki.mozilla.org/Firefox3.1/control_tab#New_Beltzner_Proposal>: "Ctrl-shift-tab" keypress should instantly switch to the "Show all N tabs" button, and thus the tabsearch UI

Which was a proposal. I don't know if there was more discussion about this topic. If you could point me to such a place it would be nice. Otherwise adding the uiwanted keyword to the bug so we can get another feedback from the ux team. With the current behavior we don't allow switching tabs in a reverse order like it is possible for switching applications.

The reverse order isn't all that interesting with MRU. It would give you "least-recently used" tabs.

At least what I can see on OS X pressing Shift+Cmd+Tab will switch to the last application in the list and iterates backward through the list.

If Mac is like Windows it only goes through tabs 1-8 not all of the tabs, it is a very much unwanted feature and was, I believe reported that it would be distributed with the function turned off, meaning you were to be surprised later. browser.ctrlTab.previews False to restore normal behavior A Linux user is reporting Ctrl+1 through 9 does not work, though that works in Windows. You can do a Google search on browser.ctrlTab.previews and find some hits,l and I think most comments are negative, it certainly doesn't work for people who really make use tabs so who is it supposed to help then.

Alex, can you please verify the uiwanted request? Thanks.

Yes, this breaks both consistency (that's not how it works in any OS, shift always means that you should traverse the stack backwards) and mode error principles.