Do you mean that when you start Firefox, those windows that it automatically restores don't have the arrows, but any new window you create and add more tabs than can fit the screen will correctly show the arrows?

That sounds like a bug. What happens if you close those original windows that were restored and only use the "new" window? Will restoring that new window retain its arrows?

It works when starting a new session (ie new window with 11+tabs) and then restoring that session.

I don't think I understand under what circumstances you say it doesn't work, then. Could you please clarify? Maybe even submit a screencast through http://www.techsmith.com/download/jing/default.asp and publish it here? Thanks!

The time it worked I completely closed all the "original restored" windows and made a new window with more than 11 tabs. This new window had the left/right arrows for scrolling through the tabs. They also appeared when I forced quit firefox and restored using session restore addon.

This is only happening to my previous sessions. Any new session is working fine.

Also my os is mac.

You may have opened a pop-up in the problematic window.

If it happens again the it is usually best to open a new window and drag the tabs to that window.

You can also try to reset the toolbars.

• http://kb.mozillazine.org/Corrupt_localstore.rdf
• https://support.mozilla.org/kb/Toolbar+keeps+resetting