Double tap to sleep

[SteelSteve]

I know the phone does double tap to wake, however all the video's / reviews I've seen claimed you could also double tap in the windows bar to sleep / close. I have tried several time and this is not working on my phone. Did I miss interpret the reviews or am I doing something wrong. I looked under touch in the settings and it only shows double tap to wake.

 

[Alfa Kapa]

It is a future of WP8.1 update 2 for phones with hideable on screen buttons.
This means that if you have update 2 installed, you should be able to double tap the blank spaces of navigation bar to lock you phone.

 

[SteelSteve]

Doesn't the 640 XL come with WP8.1 update 2?

 

[SteelSteve]

Found it, there is an option under settings\navigation bar