Password or PIN protection for config menu

Was just thinking if there could be a password or PIN setup for the config menu. Would stop any unauthorised person messing up any settings. And/or add an input that once high would lock the UI but still let inputs, IR, sensors etc react and operate as normal.

Sounds like the start of another fantastic idea for a usermod.
If a usermod like that finds enough user support, it could get put into the main code.