onVerticalDragStart method
void
onVerticalDragStart()
Implementation
void onVerticalDragStart() {
final phase = _state.phase;
if (phase == OverlayPhase.idle || phase == OverlayPhase.appearing) return;
_overlayController.stop();
_expandController.stop();
_horizontalSnapController.stop();
_verticalIntent = _VerticalIntent.none;
_state = _state.copyWith(isDragging: true, velocity: 0.0);
notifyListeners();
}