For the beta to quick taps on the home button would shrink the screen down for better one handed operation. Since the beta that doesn't seem to work. Has the access method changed? Or is it no longer available?
Ok, so yes, it's turned on, as it was before, but the double tap no longer works. I should point out that I do use nova launcher, but a did before too and it worked fine before.
OK that maybe a compatible issue, I'm not sure as I use stock launcher. Have you tried using stock launcher to see if that works. Not sure how much messing about that would be for you