Double tap to wake. LG‘s done it. So has HTC. Several others, too. It’s faster and doesn’t need as much effort as pressing a button. Previous Nokia Lumias have this feature — particularly talking about the pre-Windows 10 Mobile handsets. It’s not on the Lumia 950. Neither on the Lumia 950 XL.
So, when Microsoft’s Gabriel Aul, who was promoting progress on a debug effort, answers a tweet requesting the double tap feature on the Lumia 950 XL as such: