function openwin(url,width,height) {
	if (!width) width = 400;
	if (!height) height = 200;
	var newwin = null;
	LeftPosition = (screen.width) ? (screen.width-width)/2 : 0;
	TopPosition = (screen.height) ? (screen.height-height)/2 : 0;
	newwin = window.open(url,"newwin","width="+width+",height="+height+",resizable,scrollbars,left="+LeftPosition+",top="+TopPosition+"");
}

function show_block(block_name,status) {
	if (document.getElementById) {
		document.getElementById(block_name).style.display = (status == false) ? 'none' : 'block';
	}
}

/* Usage:
<script>
var imgs = {
image1:"image1.jpg",
image2:"image2.jpg"
};
ImgPreload(imgs);
</script>
<a onmouseover="ImgOver('image1','image2');" onmouseout="ImgOut('image1');" onclick="return false;" href="#"><img src="image1.jpg" border="0" alt="" name="image1"></a><br>
*/
var ImgLoaded=new Array();
function ImgPreload(imgArray) {
	for (var val in imgArray) {
		ImgLoaded[val] = new Image();
		ImgLoaded[val].src = imgArray[val];
	}
}
function ImgOver(imgName,imgName2) {
	document.images[imgName].src = ImgLoaded[imgName2].src;
}
function ImgOut(imgName) { 
	document.images[imgName].src = ImgLoaded[imgName].src;
}