// 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 || 85;  
 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';  
}
}