I'm trying (unsuccessfully) to get the node from a disclosure button clicked
I think this function is the more appropriate:
func outlineViewItemDidExpand(_ notification: Notification) {
let nodeToExpand = notification.userInfo as! Node
let nodeToExpand2 = notification.userInfo["NSObject"] as! Node
//Error @selector(_outlineControlClicked:) from sender NSButton 0x10053d710
}