if unbounded scrolling is not checked
the scrolling still stops at the location it would at 100% zoom even if you're zoomed in, and it has more wiggle room at the greater zoomed in view
a user was requesting help with this problem at this topic:
http://www.scirra.com/phpBB3/viewtopic.php?f=3&t=4492
there is a solution in my reply, but it involves a few events that may not be immediately obvious to a new user, and the behavior provided by these extra events is what you would expect it to do normally