pinchMoveThreshold property
Pinch Move threshold default is 40.0 (note: this doesn't take any effect
on drag) Map starts to move when pinchMoveThreshold has been achieved or
another multi finger gesture wins which allows
MultiFingerGesture.pinchMove Note: if interactiveFlags
doesn't contain
InteractiveFlag.pinchMove or enableMultiFingerGestureRace is false
then pinch move cannot win
Implementation
final double pinchMoveThreshold;