How to achieve Apple's Reachability one-handed mode on your Android phone (root req'd)
With the giant for its 5.5" screen diagonal iPhone 6 Plus, Apple introduced a dedicated one-handed usage mode, called Reachability.
The new regime is evoked by double-tapping the home key, and slides the top half of the interface down within the reach of your thumb, so you can easily key in that website or email address, and then the UI would spring right back up.
It's a great way to use the top half of the screen, instead of having to stretch your thumb all the way up, risking to drop the phone. What about Android, though, can we have this feature there?
Well, we all know how flexible Android is, especially if you root your device, and with a little bit of trickery you can get a feature very similar to Reachability up and running. Here's what needs to be done:
1. Install the Xposed framework on your rooted device, and download the One-Hand Mode module from the Play Store, then activate it and restart;
2. Play around with the One-Hand mode settings until you reach the desired height for the UI to slide down, putting a value only for the Top field:
3. Using Tasker, set a shake up-down gesture as the initiator for the One-Hand Mode app, which will in turn slide the whole interface down to your preset height value. That's it - granted, setting this is not for the average user, and it won't make the phone smaller, but will make your life with it a lil' bit easier.
source: snorrski (XDA-Devs)