// JavaScript Document
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';  }}