function windowURLCentered(url, winwidth, winheight, param)
{
    var date = new Date();
    var name = date.getTime();
    var win = openWinCentered(name, url, winheight, winwidth, param);
    }
function openWinCentered(winname, loc, heightt, widthh, params)
{  
    tp=Math.ceil((screen.height-heightt)/2);
    lf=Math.ceil((screen.width-widthh)/2);
    if (params.length > 0) params = "," + params;
    return window.open(loc,winname,"width="+widthh+",height="+heightt+",top="+tp+",left="+lf+params);
}