abstract sclass DynFullscreen > DynModule {
  transient JFrame fullScreenFrame;
  
  void goFullscreen enter {
    if (fullScreenFrame != null) ret with activateFrame(fullScreenFrame);
    fullScreenFrame = showFullScreen(fullscreenVisualize());
    onFrameClose(fullScreenFrame, r { fullScreenFrame = null; });
  }
  
  JComponent fullscreenVisualize() { null; }
  
  void exitFullscreen enter {
    disposeFrame(fullScreenFrame);
  }
  
  // works only when we are in fullscreen mode
  void setFullscreenComponent(JComponent c) enter {
    setFrameContents(fullScreenFrame, c);
  }
  
  // switch to result of fullscreenVisualize()
  void defaultScreen enter {
    setFrameContents(fullScreenFrame, fullscreenVisualize());
  }
}

Began life as a copy of #1027028