Hi, I don't know if this has been discussed already but I think a WindowClosed event is missing, or, as the event model has been implemented, a windowClosed method is missing in WindowListener. In fact at the moment there is no distinction between closing and hiding a window.
Instead, it should be possible to distinguish if a window was closed by pressing the close button on the top right of the frame or if it was hidden by a setVisible(false) instruction.