Idea for Tabs with History

I have an idea that will help users identify tabs that have history and those that do not.

for example if you have 3 tabs open but you clicked a link in the middle one and went forward one page then the middle page has history as you can navigate back but the other 2 tabs do not.

If your tab got higher (perhaps an image that looks like multiple tabs as if in a filing cabinet) then you could quickly tell at a glance if the tab you're on has history.