if (document.images) {

      button13     = new Image ();
      button13.src = "http://www.polyfone-ringtones.nl/images/subnav_populair.gif";

      button14     = new Image ();
      button14.src = "http://www.polyfone-ringtones.nl/images/subnav_populair_on.gif";

      button15     = new Image ();
      button15.src = "http://www.polyfone-ringtones.nl/images/subnav_nieuwste.gif";

      button16     = new Image ();
      button16.src = "http://www.polyfone-ringtones.nl/images/subnav_nieuwste_on.gif";

      button17     = new Image ();
      button17.src = "http://www.polyfone-ringtones.nl/images/subnav_alfabetisch.gif";

      button18     = new Image ();
      button18.src = "http://www.polyfone-ringtones.nl/images/subnav_alfabetisch_on.gif";

						
        }
	
   // this function swaps the images

function swapImage(oldButton,newButton){
   if (document.images)
      document.images[oldButton].src=eval(newButton + ".src");
}