This add-on would get 5 stars but for a few really frustrating things. Worst is that the labels for each window (and the colors) don't remain. Instead each label becomes whatever is the open tab in its group. The most recent time I opened Firefox the labels were scrambled so that they were all on the wrong group. Another issue is that the pop up opens in the center of my screen rather than on the side no matter what I have tried to move it. Also, the groups cannot be moved around and the colors are awful. On the plus side is being able to organize tabs, to move them from one group to another and to be able to close them from within the add-on. IMHO with a few fixes this would be a great organizing tool.