Add hidden mode for amounts

[Fierillo]

Android 11, Motorola One Fusion

Suggestion: add hidden mode for ammounts.

Will be nice to hide ammount with a "slice" gesture. Something similar to Muun slice. I know that Muun is shit but will nice to copy the good things.

Thanks guys for doing the best LN wallet!

[hsjoberg]

Great suggetsion.
Implemenation done in #1418 for the overview screen. Other screens are not done (yet), but may not be necessary.

Not sure what a slice gesture is but you can long-press balance and there is a toggle setting for it in settings -> General

[Fierillo]

Not sure what a slice gesture