function OpenCenterWindow( sUri, iWidth, iHeight )
{
        var sWindowName = 'win' + Math.floor( Math.random()*1000 )
        var iRealWidth = iWidth ? iWidth : 600
        var iRealHeight = iHeight ? iHeight : screen.height - 300

        var iLeft = Math.round( (screen.width-iRealWidth)/2 )
        var iTop =  Math.round( (screen.height-iRealHeight)/2 ) - 35

        var sWindowOptions = 'status=yes,menubar=no,toolbar=no'
        sWindowOptions += ',resizable=no,scrollbars=no,location=no'
        sWindowOptions += ',width='  + iRealWidth
        sWindowOptions += ',height=' + iRealHeight
        sWindowOptions += ',left='   + iLeft
        sWindowOptions += ',top='       + iTop

        var oWindow = window.open( sUri, sWindowName, sWindowOptions )
        oWindow.focus();
        return oWindow
}