Nice app, I'm really happy that TimePIN obtained a new life.
Some very small suggestions.
1. Is it possible to add hours shift as well as minutes shift? I've tried to trick like 610 minutes meaning +1 hour and +10 minutes but unfortunately only two digits for shift are allowed.
2. Why are you dealing with "adding" and "subtracting"? I think it would be easier to put a parameter "shift" which can be either positive ("addition") or negative ("subtraction").
3. The notification should not have any name. "Droidlock active" clearly shows it is installed and potentially decreases security. Our at least add an option to make the notification zero like it was in TimePIN.
4. No one is interested what is default offset value - it's better to show currently set value in brackets.
Will test later. And thanks once again.
P.S. One bug already found. For example: 24H, 20:56, time shift +15 minutes gives 2111, but should give 2071. Maths is maths and time is time, so 2056 + 15 = 2071, not 1 hour 11 min. Or at least this logic must be switchable in settings.