var isIMG = document.images;
var Arrowon;
var Arrowoff;

if (isIMG) {
   Arrowon = new Image(12,12);
   Arrowon.src = "/includes/themes/css1/images/arrow_over.gif";
   Arrowoff = new Image(12,12);
   Arrowoff.src = "/includes/themes/css1/images/arrow_down.gif";
}
function Arrow(Arrowname) {
   if (isIMG) {
      if (document.getElementById(Arrowname).src.indexOf('arrow_over.gif') != -1 )
           document.getElementById(Arrowname).src ='/includes/themes/css1/images/arrow_down.gif' ;
      else
           document.getElementById(Arrowname).src ='/includes/themes/css1/images/arrow_over.gif';
   }
}