dojo.addOnLoad(function() {
	ksPreloadImages();
	
	var menu_symbol_element = dojo.byId("menu_symbol");
	var menu_symbol_img_element = dojo.byId("menu_symbol_img");
	
	dojo.query("#menu a").forEach(function(a_element) {
		var suffix = a_element.id.slice(5);
		var nonHoverBg = dojo.style(a_element, "backgroundImage");

		a_element.onmouseover = function(event) {
			dojo.style(a_element, "backgroundImage", "url('menu_bg_black.png')");
			dojo.style(menu_symbol_element, "visibility", "visible");
			dojo.style(menu_symbol_element, "display", "block");
			menu_symbol_img_element.src = "menu_symbol_" + suffix + ".png";
		};
		
		a_element.onmouseout = function(event) {
			dojo.style(a_element, "backgroundImage", nonHoverBg);
			dojo.style(menu_symbol_element, "visibility", "hidden");
			dojo.style(menu_symbol_element, "display", "none");
		};
		
	});
	
});

function ksPreloadImages() {
	var img1 = new Image();
	img1.src = "menu_symbol_home.png";
        var img2 = new Image();
        img2.src = "menu_symbol_cv.png";
        var img3 = new Image();
        img3.src = "menu_symbol_oss.png";
        var img4 = new Image();
        img4.src = "menu_symbol_bi.png";
}