openPanel method
void
openPanel()
Implementation
void openPanel() {
_internal = true;
if (value.state == SlidingState.min) return;
value = value.copyWith(
state: SlidingState.min,
factor: 0.0,
offset: 0.0,
position: Offset.zero,
);
_panelVisibility.value = true;
_gesture = true;
_internal = false;
}