function zm_toggle(div_id) {
   var el = document.getElementById(div_id);
   if ( el.style.display == 'none' ) { el.style.display = 'block';}
   else {el.style.display = 'none';}
}
function zm_blanket_size(popUpDivVar, halfheight) {
   // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
   if (typeof window.innerWidth != 'undefined') {
      viewportheight = window.innerHeight;
   // IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
   } else if (typeof document.documentElement != 'undefined'
            && typeof document.documentElement.clientHeight !=
            'undefined' && document.documentElement.clientHeight != 0) {
      viewportheight = document.documentElement.clientHeight;
   // older versions of IE
   } else {
      viewportheight = document.getElementsByTagName('body')[0].clientHeight;
   }
   if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
      blanket_height = viewportheight;
   } else {
      if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
         blanket_height = document.body.parentNode.clientHeight;
      } else {
         blanket_height = document.body.parentNode.scrollHeight;
      }
   }

   var blanket = document.getElementById('zm_blanket');
   blanket.style.height = blanket_height + 'px';
   var popUpDiv = document.getElementById(popUpDivVar);
   popUpDiv_height=viewportheight/2-halfheight;//half popup's height
   popUpDiv.style.top = popUpDiv_height + 'px';
}
function zm_window_pos(popUpDivVar, halfwidth) {
   if (typeof window.innerWidth != 'undefined') {
      viewportwidth = window.clientWidth;
   } else if (typeof document.documentElement != 'undefined'
            && typeof document.documentElement.clientWidth !=
            'undefined' && document.documentElement.clientWidth != 0) {
      viewportwidth = document.documentElement.clientWidth;
   } else {
      viewportwidth = document.documentElement.clientWidth;
   }
   if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
      window_width = viewportwidth;
   } else {
      if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
         window_width = document.body.parentNode.clientWidth;
      } else {
         window_width = document.body.parentNode.scrollWidth;
      }
   }
   var popUpDiv = document.getElementById(popUpDivVar);
   window_width=window_width/2-halfwidth;//half popup's width
   popUpDiv.style.left = window_width + 'px';
}
function zoom_popup(windowname, halfwidth, halfheight) {
   window.scrollTo(0,0);
   zm_blanket_size(windowname, halfheight);
   zm_window_pos(windowname, halfwidth);
   zm_toggle('zm_blanket');
   zm_toggle(windowname);
}