Marco Arment on Twitter:

I needed custom pointInside:withEvent: behavior to minimize the scroll bar's interference with the web view's tap zones for a 4.0.1 fix.

Excellent. That’s my second biggest annoyance with Instapaper 4.0. I tap on, or swipe from, the right edge of the screen and the page doesn’t turn. Temporary workaround is to hold iPhone in left hand.