I just upgraded from 1.0.4 to 1.0.5 and now middle-click doesn't open in tabs. Right-click and select it from the menu still works. I've got TabMix installed, thought it might be that causing the problem. Upgraded to the latest version of that, which said something about fixing a middle-click problem.
I've re-checked the extension options and the Firefox options. No luck. Out of ideas. Pointers for what to look at?