function grayOut(vis, options) {
var options = options || {}; 
var zindex = options.zindex || 50;
var opacity = options.opacity || 50;
var opaque = (opacity / 100);
var bgcolor = options.bgcolor || '#000000';
var dark=document.getElementById('darkenScreenObject');
if (!dark) {
var tbody = document.getElementsByTagName("body")[0];
var tnode = document.createElement('div');           
tnode.style.position='absolute';                 
tnode.style.top='0px';                           
tnode.style.left='0px';                          
tnode.style.overflow='hidden';                            
tnode.style.display='none';                      
tnode.id='darkenScreenObject';                  
tbody.appendChild(tnode);                            
dark=document.getElementById('darkenScreenObject');  
}
if (vis) {
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%';
}   
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';
}
}