Was looking for an add-on to do just this. Thank you. I suggest making a light multi-color for other open tabs to easily keep track of which tabs are which, Marking specific tabs with a color of your choosing for each tab the user wants to remember or keep track of; so when not the active tab, you can color & find inactive tabs by the color the user sets..... Even better add multi-color choice selection (2 tone maybe) for those inactive tabs to give more variety and more distinct recognition to find multiple various tabs. ( I believe this will get a lot more recognition for & draw more people to appreciating & noticing this useful Add-on .... just a thought).