function checkAdblock() {
	if ( detectAdblock() ){
		trackAdblock('Adblock Detected');
	} else {
		trackAdblock('No Adblock');
	}
}
 
//adapted from http://stackoverflow.com/questions/2472/how-can-i-tell-if-a-web-client-is-blocking-ads
function detectAdblock(){
	//Create an invisible test image 
	var AbpImage = document.createElement("IMG");
	AbpImage.id = 'abp_detector';
	AbpImage.src = '/images/ad/banner.gif';
	AbpImage.style.width = '0px';
	AbpImage.style.height = '0px';
	AbpImage.style.top = '-1000px';
	AbpImage.style.left = '-1000px';
	document.body.appendChild(AbpImage);
	//Check if Adblock has tried to hide the image
	var AbpDetected = (ws_getComputedStyle(document.getElementById('abp_detector'),'display') == 'none');
	//Be nice - remove the image 
	document.body.removeChild(AbpImage);
	return AbpDetected;
}
 
//http://www.robertnyman.com/2006/04/24/get-the-rendered-style-of-an-element/
function ws_getComputedStyle(oElm, strCssRule){
	var strValue = "";
	if(document.defaultView && document.defaultView.getComputedStyle){
		strValue = document.defaultView.getComputedStyle(oElm, "").getPropertyValue(strCssRule);
	}
	else if(oElm.currentStyle){
		strCssRule = strCssRule.replace(/\-(\w)/g, function (strMatch, p1){
			return p1.toUpperCase();
		});
		strValue = oElm.currentStyle[strCssRule];
	}
	return strValue;
}
 
//Record Adblock state  
function trackAdblock(state){
 
	function readCookie(name) {
		var nameEQ = name + "=";
		var ca = document.cookie.split(';');
		for(var i=0;i < ca.length;i++) {
			var c = ca[i];
			while (c.charAt(0)==' ') c = c.substring(1,c.length);
			if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
		}
		return null;
	}
 
	var current_cookie = readCookie('__utmv');
	if ( (current_cookie==null) || (current_cookie.indexOf(encodeURIComponent(state)) == -1) ){
		//Set the user-defined segmentation variable with the Google Analytics tracker
		if (typeof pageTracker != 'undefined'){
  			pageTracker._setVar(state);
	  	}
	}
}