jQuery(document).ready(function($){
	
	var navigation_timer	= null;
	var navigation_current	= null;
	
	$('#main_menu  > ul > li')
		.mouseover(function(){
			if(navigation_timer){
				clearTimeout(navigation_timer);
				if(navigation_current != this){
					$(navigation_current).find('ul').css('display', 'none');
				}
			}
			
			$(this).find('div').css('display', 'block');
			
			navigation_current = this;
		})
		.mouseout(function(){
			navigation_timer = setTimeout(function(){
				$(navigation_current).find('div').css('display', 'none');
			}, 500)
		})
});