This is a MS Windows only Addon
I wanted to switch to Firefox BUT Ancestry.com have an advanced image viewer that only works in MSIE - you can see census etc images in FF but they are better in MSIE
IE Tab also allows FF to behave like MSIE. Simply it puts an icon on bottom right status line - its Firefox when Firefox and click to make it MSIE.
I also like Table2Clipboard and I use that to paste Ancestry data lists of people in census - so that needs to be Firefox - so I only click IE Tab when I want to look at an image.
IE Tab cannot provide a navigation history
So this is how I use - I leave Ancestry as FF - do not put in IETab list of sites - then I get the navigation history - when I want to see an image - click right on image icon and select Open in IETab - it is wonderful