Uniform Highlighting Technique

• Old approach: each shape draws its selection state
• Inconsistent
  
• Better approach: shift, draw, shift, draw, restore to original position
  
• Define in SelectableShape
  public void drawSelection(Graphics2D g2)
  {
     translate(1, 1);
     draw(g2);
     translate(1, 1);
     draw(g2);
     translate(-2, -2);
  }