minutes property
Moves the thumbs based on minutes.
For example, if min is DateTime(2000, 01, 01, 05, 10) and
max is DateTime(2006, 01, 01, 05, 40) and SliderDuration(minutes: 10)
then the thumb will get moved at DateTime(2000, 01, 01, 05, 10),
DateTime(2000, 01, 01, 05, 20), DateTime(2000, 01, 01, 05, 30),
and DateTime(2000, 01, 01, 05, 40).
Implementation
final int minutes;