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';
	 document.getElementById("L1").style.display="none";
	 
  }
}



document.onkeydown = KeyCheck;   
document.onkeyup = clear_check;     
var check = false;
var check1 = false;
var check2 = false;
var check3 = false;

function clear_check(){

	check = false;
	check1 = false;
	check2 = false;
	check3 = false;

}

function KeyCheck(e)

{

  
   var KeyID = (window.event) ? event.keyCode : e.keyCode;

//alert(KeyID);
   switch(KeyID)

   {
	//alert(KeyID);
      case 16:

      check = true;

      break; 

      case 17:

      check1 = true;

      break;

      case 18:

      check2 = true;

      break;

      case 76:

      check3 = true;

      break;

      
   }
   
   if(check && check1  && check3) {
   
   grayOut(true,{'opacity':'25'});
   document.getElementById("L1").style.display="";
   
   }

}




var xhrFoodChainCat = false;

	function updateLocation(){
		
		
		
		if(window.XMLHttpRequest){
			
			try {
				
				xhrFoodChainCat = new XMLHttpRequest();
        	
			} catch(e) {
			
				xhrFoodChainCat = false;
        	
			}
		
		}else{
			
			try{
				
				xhrFoodChainCat = new ActiveXObject("Microsoft.XMLHTTP");
				
			}catch(e){
				
				xhrFoodChainCat = false;
			
			}
		
		}
		
		if(xhrFoodChainCat) {
		
		
			xhrFoodChainCat.onreadystatechange = showLocation;
			
			var district = document.getElementById("district").value;
			
			xhrFoodChainCat.open("POST","get_location.php",true);
			
			xhrFoodChainCat.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); 
			
			xhrFoodChainCat.send("ajax=1&district=" + district);
		
		}else{
			
			
			
		}
		
	}
	
	
	function showLocation(){
		
		
		if(xhrFoodChainCat.readyState == 4) {
			
			if(xhrFoodChainCat.status == 200){
				
				document.getElementById("locationContainer").innerHTML = xhrFoodChainCat.responseText;	
					
				
			}else{
				
				document.getElementById("locationContainer").innerHTML = "Some error occured.";
				
			}
			
		}else{
			
		//	document.getElementById("locationContainer").firstChild.disabled = true; 
			
			document.getElementById("location").disabled = true; 
			
		}

		
	}