If I happen to have clicked my middle mouse button to scroll upwards on a webpage, it's frustrating that, given that I'll tend to put the mouse right to the top of the screen in order to scroll quickly, another middle-click to exit the auto-scroll mode also ends up closing the tab that the mouse cursor was inevitably over.
To the best of my awareness, this does not occur in e.g. Firefox's auto-scroll mode.
It would be cool if inhibition of this behaviour were considered, if not necessarily as standard behaviour, but at least as an option, for implementation in a future release.