var navArrowSlider = function(navWrap, navPos, navElementsArray, activeID,  arrowY, leftOffset) {
	var youAreHere = new Fx.Tween($(navWrap), {
		duration: 800,
		transition: Fx.Transitions.Expo.easeOut  //adjust transition effect here
	});
	var youAreHere2 = new Fx.Tween($(navWrap), {
		duration: 800,
		transition: Fx.Transitions.Pow.easeOut  //adjust transition effect here
	});
	$$(navElementsArray).each(function(item){
		item.addEvent('mouseenter', function() {
			
			if (navigator.appName != 'Microsoft Internet Explorer')
			  leftOffset = 0;
			var thisPos = item.getPosition(navPos).x - leftOffset;
			var thisSize = item.getSize(navPos).x + 8;
			youAreHere.cancel();
			youAreHere2.cancel();
			youAreHere.start('margin-left', (thisPos-5) + 'px');;
			youAreHere2.start('width',thisSize + 'px');
		});
	});
	var currentArrow = function() {
		youAreHere.cancel();
		youAreHere2.cancel();
		
		if (navigator.appName != 'Microsoft Internet Explorer')
			  leftOffset = 0;
			
		//correct IE rendering problem (without this, it wont go to the active nav onload)	
		if($(activeID)!=undefined){
			var activePos = $(activeID).getPosition(navPos).x - leftOffset;
			youAreHere.start('margin-left', (activePos-5) + 'px');
			var activeSize = $(activeID).getSize(navPos).x + 8;
			youAreHere2.start('width',activeSize + 'px');
		}
	};
	
	//correct IE rendering problem (without this, it wont go to the active nav onload)	
	if($(activeID)!=undefined){
		
		var activePos = $(activeID).getPosition(navWrap).x  + $(activeID).getSize().x - leftOffset; 
		$(navWrap).setStyle('background-position', activePos + 'px ' + arrowY + 'px');  
	}
	//works to set image to starting position in other browsers
	currentArrow(); 
		$(navPos).addEvent('mouseleave', currentArrow);
	
}; 
window.addEvent('domready', function() {
	navArrowSlider(
		'naw_font', // ID of nav wrap
		'menu_header',
		'#menu_header ul li', // Array selector of nav elements
		'active_nav', // ID of current nav element
		'20', //  Background position y of background image
		'0' //  INT ONLY - How far left from the right edge of the nav element that the image settles
	);
});