open method
Open the dropdown menu.
if onOpened
is provided, it would be called after the menu is opened.
Implementation
void open({VoidCallback? onOpened}) {
if (isOpen || _currentAttachedState == null) return;
_menuOverlay = _currentAttachedState!.buildMenuOverlay();
Overlay.of(_currentAttachedState!.context).insert(_menuOverlay!);
onOpened?.call();
}