function centerWindow(url,w,h){
if ((document.all) || (document.getElementById))
var xMax = screen.width, yMax = screen.height;
else
if (document.layers)
var xMax = window.outerWidth, yMax = window.outerHeight;
else
var xMax = 640, yMax=480;
var xOffset = (xMax - w)/2, yOffset = (yMax - h)/2;
if (top.objWindow){
if (!top.objWindow.closed){
top.objWindow.resizeTo(w,h);
top.objWindow.location=url;
}else{
top.objWindow=window.open(url,'popup','width='+w+',height='+h+',screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+',scrollbars=no');
}
}else{
top.objWindow=window.open(url,'popup','width='+w+',height='+h+',screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+',scrollbars=no');
}
top.objWindow.focus();
}