handle ToolkitClose() in plugins

action.go

@@ -172,6 +172,9 @@ func (me *TreeInfo) doAction(a widget.Action) {
 		}
 		me.DeleteNode(n)
 		// now remove the child from the parent
+	case widget.ToolkitClose:
+		log.Info("tree.ToolkitClose()")
+		me.ToolkitClose()
 	default:
 		log.Log(TREEWARN, "tree.Action() unknown action", a.ActionType, "on wId", a.WidgetId)
 		// me.NodeAction(n, a.ActionType)