It would be super to nice to be able to right click a tab, select 'color' and then choose one of, say, nine predefined colors from the sub-menu.
This is useful for people like me who often have a lot of files open and want to be able to visually/mentally group files. Even if it's just to mark "currently working on these files".
This is different to other suggestions wanting tab colour by file type or inactivity.
Customer support service by UserEcho