Reachability feature like in iPhone 6 I've got Nexus 4 and not big enough hands to be able to fully control my phone with one hand. I've seen an amazing feature on iPhone 6 called "Reachability mode" (when home button is double tapped, whole UI shifts down to a thumb's reach).

Is there an Android app creating similar reachability mode? I don't have my phone rooted but I can do so.

For all the trolls: please don't write me 'buy an iPhone' not even Samsung, that's not the answer to this question.

Thank you very much!
Actually, here is a research paper doing it on android before Apple implemented it, but better ;-)
Go to minute 1:05
Backpat: improving one-handed touchscreen operati…: http://youtu.be/6obUW7uhWOk

Not that the platform matters, though. It's a usability feature for a form factor after all.