model.addPropertyChangeListener(Browser.SELECTED_DISPLAY_PROPERTY, this);
    BrowserControl(BrowserModel model, RootDisplay view)    {        if (model == null) throw new NullPointerException("No model.");        if (view == null) throw new NullPointerException("No view.");        this.model = model;        this.view = view;        popupTrigger = false;    }