If back, home and multitasking just aren’t enough for you on the HTC One M9, the new Sense 7 gives you the option to add a fourth button.
The ability to add and rearrange the on-screen navigation buttons on an Android smartphone isn’t exactly new — but it is new to Sense 7 on the HTC One M9. And it takes just a few taps to get the job done. Here’s how it works:
Source: iMore