function isSafari () {
	var ck = false;
	if(navigator.userAgent.indexOf("Safari") != -1) {ck = true;}	
	return ck;
}

function checkScreenWidth() {
	return screen.width;
}

function checkScreenHeight() {
	return screen.height;
}


function handle(delta) {
	main.myFunction(delta);
}

function wheel(event){

	var delta = 0;
	
	if (!event) {event = window.event;}
                   
	if (event.wheelDelta) {
		delta = event.wheelDelta/120;
		if (window.opera) {delta = -delta;}
	} else if (event.detail) {
		delta = -event.detail/3;
	}
	
	if (delta) {handle(delta);}
	if (event.preventDefault) {event.preventDefault();}
	
	event.returnValue = false;
}

function addListener() {
	if (window.addEventListener) {window.addEventListener('DOMMouseScroll', wheel, false);}
	window.onmousewheel = document.onmousewheel = wheel;
	return true;
}

function removeListener() {
	if (window.addEventListener) {window.removeEventListener('DOMMouseScroll', wheel, false);}
	window.onmousewheel = document.onmousewheel = null;
	return true;
}