anchor.diff:   * 
    * This [Node] is meant as a foreground for your game.
    * 
  - * [OverlayLayer] will cover the entire Design-space with a rectangle no
  - * matter how you transform this [Layer] as long as the [constrainBackground] flag
  - * remains true.
  + * [OverlayLayer] does NOT constrain its background.
    */
   class OverlayLayer extends Layer {
     
  
positive.code:   String overlayColor;
    
    AffineTransform t = new AffineTransform.Identity();
    /**
     * Constrain the background color to within the [Layer] itself. This
     * is the typical behavior expected.
     * Default is (true)
     */  
    bool constrainBackground = true;
    /**
     * Render a background color defined by [overlayColor].
     * Default is (true)
  
negative.code:       _ls.setValues(0.0, 0.0);
        _le.setValues(0.0, 25.0);
        context.drawLine(_ls, _le);
        
        context.drawColor = "rgba(0,255,0,1.0)";
        _ls.setValues(0.0, 25.0);
        _le.setValues(0.0, 50.0);
        context.drawLine(_ls, _le);
        
        context.restore();
      }
      
  