function grayOut(vis, options) {  
  // Pass true to gray out screen, false to ungray  
  // options are optional.  This is a JSON object with the following (optional) properties  
  // opacity:0-100         
  // Lower number = less grayout higher = more of a blackout   
  // zindex: #             
  // HTML elements with a higher zindex appear on top of the gray out  
  // bgcolor: (#xxxxxx)    
  // Standard RGB Hex color code  
  // grayOut(true, {'zindex':'50', 'bgcolor':'#0000FF', 'opacity':'70'});  
  // Because options is JSON opacity/zindex/bgcolor are all optional and can appear  
  // in any order.  Pass only the properties you need to set.

  var options = options || {};   
  var zindex = options.zindex || 200;  
  var opacity = options.opacity || 80;  
  var opaque = (opacity / 100);  
  var bgcolor = options.bgcolor || '#D0D0D0';
  var dark=document.getElementById('darkenScreenObject');
  if (!dark) {    
    // The dark layer doesn't exist, it's never been created.  So we'll    
    // create it here and apply some basic styles.    
    // If you are getting errors in IE see: http://support.microsoft.com/default.aspx/kb/927917    
    var tbody = document.getElementsByTagName("body")[0];    
    var tnode = document.createElement('div');           // Create the layer.
    tnode.style.position='absolute';                 // Position absolutely        
    tnode.style.top='0px';                           // In the top        
    tnode.style.left='0px';                          // Left corner of the page        
    tnode.style.overflow='hidden';                   // Try to avoid making scroll bars 
    tnode.style.display='none';                      // Start out Hidden        
    tnode.id='darkenScreenObject';                   // Name it so we can find it later    
    tbody.appendChild(tnode);                        // Add it to the web page    
    dark=document.getElementById('darkenScreenObject');  // Get the object.  
  } 
  if (vis) {    // Calculate the page width and height     
    if( document.body && ( document.body.scrollWidth || document.body.scrollHeight ) ) {
       var pageWidth =document.body.scrollWidth+'px';
      var pageHeight = document.body.scrollHeight+'px';
    } else if( document.body.offsetWidth ) {
      var pageWidth = document.body.offsetWidth+'px';
      var pageHeight = document.body.offsetHeight+'px';    
    } else {
      var pageWidth='100%';
      var pageHeight='100%';    
    }

    if (device == 'iPad') {
      pageWidth='1600';
      pageHeight='100%';
    }


//    var pageWidth = document.body.offsetWidth;
//    var pageHeight= document.body.offsetHeight + 20;

    //set the shader to cover the entire page and make it visible.
    dark.style.opacity=opaque;                          
    dark.style.MozOpacity=opaque;
    dark.style.filter='alpha(opacity='+opacity+')';
    dark.style.zIndex=zindex;            
    dark.style.backgroundColor=bgcolor;
    dark.style.width= pageWidth;
    dark.style.height= pageHeight;
    dark.style.display='block';                            
  } else {
    dark.style.display='none';
  }
}