We have released another version TooManyTabs 1.3.1 today, this fix will make TooManyTabs compatible with Beta 7 now. The incompatibility is caused by some changes on how the tab is rendered. (For others extensions developers' reference, the tabs binding has changed)
I am not sure whether this fix will work for Beta 8, 9, 10... etc. If you would like to help our development, please let us know if you find any problem when using TooManyTabs in Firefox 4 (and Firefox 3).
Also, there are some cosmetic changes for Firefox 4. If you have "tabs on tab" enabled, TMT toolbar will be right under the tab bar.
Other bug fix:
- Fix backup and restore TooManyTabs tabs in 1.3.0
- Optimize scripts loading on Firefox Startup