The new autoscroll feature in gtk+ 3.10 (Bug 704703), in my typical use, is accidentally triggered because I apparently don't move the mouse fast enough once I grab the scrollbar.  This typically happens when I grab the scrollbar look back at the text before moving the mouse so I can watch the view change.

It would seem that this feature might be better implemented as being enabled when the user right clicks and pauses on the location indicator and not change existing left click behavior based on a time related event.  The problem is once this is triggered if you didn't want it to occur you have to release the mouse button and try again which has a negative usability aspect to it.