Cannot easily drag to min or max

[mudar]

Thanks for the excellent library 👍 I guess you don't have much time for maintenance, so I'm just creating this issue here to reference it in an upcoming pull request.

Issue:
When dragging the handle to the start or end points, progress is not always set to zero or max, leaving a small offset. Usually happens when initial value is not min/max. In this case, I need to retry a couple of times, dragging slowly trying to get the right position...