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

function flip() {
	var imgid = document.getElementById('flipimg');
	var blackimg = imgid.src;
	var colorimg = blackimg.replace('_black-trans.png','_color-trans.png');
	var preloadimg = new Image();
	preloadimg.src = colorimg;
	imgid.onmouseover = function() {
		imgid.src = colorimg;
	}
	imgid.onmouseout = function() {
		imgid.src = blackimg;
	}
}

addLoadEvent(flip);