I defined a URL widget NOT as a pop-up, closable. I entered an action to hide/show some widgets and buttons on Close of the URL widget. I tested it and it did not work. I went back into NAB and the action I had defined on Close of the URL widget was gone.
If I define the URL widget as a pop-up and enter the action on Close of the URL widget it works.
If I define the URL widget as a pop-up and enter the action on Close of the URL widget it works.