protected void installDesktopManager() {
   desktopManager = desktop.getDesktopManager();
   if (desktopManager == null) {
     desktopManager = new BasicDesktopManager();
     desktop.setDesktopManager(desktopManager);
   }
 }
 public void removeInternalFrame(JInternalFrame internalFrame) {
   // Looks like #closeFrame is the proper way to remove an internal
   // frame.
   // It will activate the next frame. [Jon Aquino]
   desktopPane.getDesktopManager().closeFrame(internalFrame);
 }
 protected void uninstallDesktopManager() {
   if (desktop.getDesktopManager() instanceof UIResource) {
     desktop.setDesktopManager(null);
   }
   desktopManager = null;
 }