private void definePanels(UIDefaults d){
  String p="Panel";
  d.put(p + ".contentMargins",new InsetsUIResource(0,0,0,0));
  d.put(p + ".background",new ColorUIResource((Color)d.get("control")));
  d.put(p + ".opaque",Boolean.TRUE);
}

private void definePanels ( UIDefaults d ) { String p = "Panel" ; d . put ( p + ".contentMargins" , new InsetsUIResource ( 0 , 0 , 0 , 0 ) ) ; d . put ( p + ".background" , new ColorUIResource ( ( Color ) d . get ( "control" ) ) ) ; d . put ( p + ".opaque" , Boolean . TRUE ) ; }
initialize the panel settings .
