var jsc = new Cookies(); 
tracker.sip = function(preview) {
	if (!jsc.get('popup_shown')) {
		if (!this.invitePopupVisible){
		var popup = this.getInvitePopup(true);
		if (popup){
			if (typeof popup.style.opacity !== 'undefined'){
				var opacity = 0;
				popup.style.opacity = 0;
				popup.style.display = 'block';
				var offset = Math.round(popup.clientHeight / 2);
				popup.style.marginTop = '-' + offset + 'px';
				var iter = function (){
					if (opacity < 1){
						opacity = opacity + 0.1;opacity = opacity > 1 ? 1 : opacity;popup.style.opacity = opacity;
						setTimeout(iter, 40);
					}
				};
				iter();
			} else {
				popup.style.display = 'block';
				var offset2 = Math.round(popup.clientHeight / 2);
				popup.style.marginTop = '-' + offset2 + 'px';
			}
		}
		this.invitePopupVisible = true;
					
		jsc.set('popup_shown', 'true', 30);
		}
	}
}