I was very happy to see this extension, I had a similar one a long time ago that stopped working. It would be a great feature - if it worked. Unfortunately, there are major bugs and the developer hasn't responded for months. According to his profile, he's in Ukraine, so I hope things are ok with him. It's a good idea, but too buggy to use. Colours get applied to the wrong tabs, or in a different window, don't restore correctly after restart, etc.