NewWindow = null;

function new_window(width, height, src, settings)
{
    if(NewWindow){NewWindow.close();}	
    if(NewWindow==null || NewWindow.closed)
    {
        if (settings == false)
        {
            settings="left=10, top=20, width=" + width +", height=" + height +", toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no,resizable=no";
        }   
        NewWindow = window.open(src,'',settings);
    }

    NewWindow.focus();
}