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';
    }
}