onClose property

Called when the menu begins closing.

Fires immediately when a close is triggered — tap outside the barrier, re-tapping the trigger button, or selecting a menu item — before the close animation completes. Use this to synchronise external state (e.g. stopping a morph controller) that should react as soon as the close gesture is confirmed.

If you need to act only after the animation has fully settled, listen to GlassMorphController status changes directly.