function openwindow (url, target, width, height)
{
	if (width > 950) width = 950;
	if (height > 750) height = 750;
	
	xpos = (screen.availWidth - width)/2;
	ypos = (screen.availHeight - height)/2;
	
	window.open(url, target, "width=" + width + ",height=" + height + ",left=" + xpos + ",top=" + ypos + ",scrollbars=1,menubar=0,status=1,toolbar=0,resizable=1").focus();
}