Intermittently only some components refresh (variant on version 1)

This is a variant of the bug report applet at this link, in which two setVisible lines were used as an attempted workaround.  However, the refresh  problem remains on the Macintosh.  The new lines are indicated in bold:

if (ae.getSource() == b)
{
   labelPanel.setVisible(false);
   labelPanel.removeAll();
   addElements();
   labelPanel.setVisible(true);
   validate();
}

Full source code

The contact person about this test page is Mickey Segal.  A listing of  many Java resources is at this link