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 || 50;
  var opacity = options.opacity || 70;
  var opaque = (opacity / 100);
  var bgcolor = options.bgcolor || '#000000';
  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%';
	}   
	//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';
  }
}