var menuSlider;
function MenuSlider()
{	
	this.menu = $('#menu_slider');
	this.holder = $('#wrapper');
	this.top = parseInt(this.menu.css('top'));
	
	this.animation = null;    //pohyb menu na cielovu poziciu
	this.previousPostion = 0; //predch. nascrolovana pozicia
	this.inactiveTime = 0;
	this.inactiveTimeTreshold = 1; //necinnost po scrolovani 
	
	
	setInterval(function() {menuSlider.checkPositon()}, 100);
} 

MenuSlider.prototype.checkPositon = function()
{
	var scrollOffsetsTop = $(window).scrollTop();
	if(scrollOffsetsTop != this.previousPostion)
	{
		this.inactiveTime = 0;
		if(this.animation)
		{
			this.animation.cancel();
			this.animation = null;
		}
	}
	else
	{
		this.inactiveTime++;
	}
	this.previousPostion = scrollOffsetsTop;
	
	if(this.inactiveTime > this.inactiveTimeTreshold)
	{
		this.moveMenu();
	}
	
	
}

MenuSlider.prototype.moveMenu = function()
{
	var newPosition = $(window).scrollTop();
	newPosition = Math.max(this.top, newPosition);
	newPosition = Math.min(newPosition, parseInt(this.holder.css('height')) - parseInt(this.menu.css('height')) - 20);
	if(!this.menu.css('top') || parseInt(this.menu.css('top')) != newPosition)
	{
		this.menu.css('top', newPosition + "px");
	}
}