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     
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';  }
}