Rated 4 out of 5 stars

A very useful add-on.

Just noticed a minor bug recently. I am using Session Manager 0.7.9 together with this add-on. I have these two options (among a few others) enabled:
- Add menu to panorama button
- Replace panorama button

With the Session Manager add-on enabled, I noticed just recently that the TabGroups Menu add-on does not start up (i.e. no drop-down button showing-up next to the panorama button) when I launch Firefox (was using 12, now 13). I had to disable and re-enable the TabGroups Menu add-on to get it working.

If I disable the Session Manager add-on, the TabGroups Menu add-on works as expected.

Further testing show that when I have the following settings enabled in the Session Manager, it interferes with the TabGroups Menu add-on:
- Startup & Shutdown section
- Prompt for a session
- Pre-select previous session

It looks like whenever the Session Manager dialog box is displayed at the beginning, prompting to select a session, the TabGroups Menu stopped working until a disable/re-enable of the add-on is performed. If I choose use the "Select Session" option and set to auto-load a session, i.e. no dialog box appeared, the TabGroups Menu add-on started without any issue.

This review is for a previous version of the add-on (