function iMap() {
	if(document.getElementsByTagName) {
		var areas = document.getElementsByTagName("area");
		var divs = document.getElementsByTagName("div");

		for(var i=0; i < areas.length; i++) {
			
				areas[i].onmouseover = function() {

					switch( this.getAttribute("class") || this.getAttribute("className") ) {
						case "button_ll": divs[1].style.zIndex = 1000; break;
						case "button_lr": divs[2].style.zIndex = 1000; break;
						case "button_rl": divs[4].style.zIndex = 1000; break;
						case "button_rr": divs[3].style.zIndex = 1000; break;
					}
				}
				
				areas[i].onmouseout = function() {

					switch( this.getAttribute("class") || this.getAttribute("className") ) {
						case "button_ll": divs[1].style.zIndex = -9999; break;
						case "button_lr": divs[2].style.zIndex = -9999; break;
						case "button_rl": divs[4].style.zIndex = -9999; break;
						case "button_rr": divs[3].style.zIndex = -9999; break;
					}
				}
		}
	}
}

if(window.addEventListener) {
	window.addEventListener("load", iMap, false);
}
else if(window.attachEvent) {
	window.attachEvent("onload", iMap);
}