title: fillOval and correct use of paintComponent in actionListener
body: <p>I want to use <code>fillOval</code> outside of <code>paintComponent</code>; for example, <code>fillOval</code> in <code>actionListener</code>:</p>
  
  <pre><code>public void mouseReleased(MouseEvent e) {
  
      int r = Math.max((maxx - minx) / 2, (maxy - miny) / 2);
      int nr = (int) Math.sqrt(2 * Math.pow(r, 2));
      int newx = minx - (nr - r);
      int newy = miny - (nr - r);
  
      iterator.add(new Object[] { newx, newy, nr, g2.getColor() });
      // remember
      paintComponent(g2);
  
  }
  </code></pre>
  
  <p>I'm not sure whether <code>paintComponent(g2)</code> is correct or not.</p>