function openWindow(url,winName,winWidth,winHeight,features) {
// This function opens a popup window centered by x and y

	x = (screen.availWidth-winWidth)/2;
  	y = (screen.availHeight-winHeight)/2;
	features += ",width="+winWidth+",height="+winHeight;
  	features += ",left="+x+",top="+y+",screenX="+x+",screenY="+y;
    newin = window.open(url,winName,features);
    newin.focus();
}