function dropShadow(){
	var canvas = document.getElementById("canvas");
	var left = document.getElementById("leftShadow");
	var right = document.getElementById("rightShadow");
	right.height = left.height = canvas.offsetHeight;
};

if (window.addEventListener != null)window.addEventListener("load",dropShadow,false);
if (window.attachEvent != null)window.attachEvent("onload",dropShadow);