function enable_slide_show(category_id) {
       var posCode = '';
       var minWidth=450;
       var minHeight=600;
       if (document.all || document.layers || document.createTextNode) {
        posX = Math.round((screen.width - minWidth) / 2);
        posY = Math.round((screen.height - minHeight) / 2);
        posCode = (document.all)? 'left='+posX+',top='+posY : 'screenX='+posX+',screenY='+posY;
       }
       cardWindow = window.open('popup.slideshow.php?category_id='+category_id,'','menubar=no,toolbar=no,scrollbars=no,status=no,width='+minWidth+',height='+minHeight+','+posCode);
      }