Called when user moves out of an item or item's icon, handle, badge or count You can add event listener during the object creation: let sidebar = new w2sidebar({ name : 'sidebar', nodes: [ { id: 'id-1', text: 'Level 1' }, { id: 'id-2', text: 'Level 2' }, { id: 'id-3', text: 'Level 3' } ], onMouseLeave(event) { console.log(event) } }) or after the object has been created: w2ui.sidebar.on('onMouseLeave', function(event) { console.log(event) }) This event is triggered to hide the tooltip over the hangle, icon, badge or count or just catch event when user moves mouse out of the item. You can find out what part of the item in action if you read `event.detail`. The event handler is called before the default action of the event is triggered. You can cancel the default action by calling event.preventDefault(). To perform an action after the event is fully processed, define event.onComplete function. See events page in utilities for more details.