Add Lock Feature for privacy / security

[DSDV]

Hello,

i love you app (:

and i want to suggest a lock feature like signal has.
you can enable it in the settings and it asks the systems unlock message upon opening the app.

So for example you would have to enter you PIN when you want to watch the gallery.
of course its no preventing someone from installing another gallery apk but its a nice convenience feature for preventing fast preying eyes (:

with kind regards