function openwin(url, width, height) 
{    if (document.all)
        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 - width)/2, yOffset = (yMax - height)/2;

	win = window.open(url, 'win', 'width=' + width + ',height=' + height + ',screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+',scrollbars=no resizable=no');
	win.focus();
}