Well, exactly what it sounds like. (^_^) In IE, you can scroll when holding the middle mouse button, instead of just using the mouse wheel. As I only have a three button mouse without wheel, this is one of the features I would like to see in Mozilla.
This is a duplicate of bug 22775. Please reopen if you disagree. Thanks *** This bug has been marked as a duplicate of 22775 ***
Clearly a dupe of that one. V DUPE