While this addon provides useful functionality, in its current state it is very buggy. I've had regular problems with tab positioning and movement, with child tabs being positioned outside of the area below the parent tab, and with the extension frequently preventing me from moving tab groups around in simple ways--being unable to reparent a tab and its children, or outright being unable to reorder top-level tabs. The functionality has been useful enough that I've worked around these problems instead of just uninstalling it, however now there is yet another problem with it. Now, the sidebar just perpetually shows a loading animation, never displaying the tabs for any of my windows. Closing and reopening the sidebar doesn't fix it. Disabling and re-enabling the addon doesn't fix it. Even uninstalling and reinstalling doesn't make it work again. As of now, all this does for me is take up a part of the side of my windows with a big blank area with a small animation in the middle of it. So, it's getting uninstalled. Hopefully this will be in a more usable state at some time in the future.