function addLoadEvent(func) {	
	var oldonload = window.onload;
	if (typeof window.onload != 'function'){
    	window.onload = func;
	} else {
		window.onload = function(){
			oldonload();
			func();
		}
	}

}

function navOver(ID) {
	
	document.getElementById(ID).src = "imgs/navi/" + ID + "-r.gif";
	
}

function navOut(ID) {
	
	document.getElementById(ID).src = "imgs/navi/" + ID + ".gif";
	
}

function initNav() {
	
	if (!document.getElementsByTagName){ return; }
	var anchors = document.getElementsByTagName("img");

	for (var i=0; i<anchors.length; i++){
		var anchor = anchors[i];
		var j = i;

		if (anchor.getAttribute("class") == "nav" || anchor.getAttribute("className") == "nav"){
			var id = anchor.getAttribute("id");
			anchor.onmouseover = function () {
				navOver(this.id);
			}
			anchor.onmouseout = function () {
				navOut(this.id);
			}
		}
	}
}

addLoadEvent(initNav);