var menuimg=new Array(4);
var buffer=new Image();

function preLoadImages() {
	for (i=0;i<4;i++) {
		menuimg[i]=new Image();
		menuimg[i].src="images/menu"+(i+2)+"s.png";
	}
}

function chImage(img1,img2) {
	buffer.src=document.getElementById(img1).src;
	document.getElementById(img1).src=img2.src;
}

function backImage(img) {
	document.getElementById(img).src=buffer.src;
}

function setFrameHeight(frameid,height) {
		document.getElementById(frameid).height=height+100;
	}