function disable_right_click(e)
{
    var browser = navigator.appName.substring ( 0, 9 );
    var event_number = 0;
    if (browser=="Microsoft")
        event_number = event.button;
    else if (browser=="Netscape")
        event_number = e.which;

    if ( event_number==2 || event_number==3 )
        {
        alert ("Imagem protegida.");
        return (false);
        }

    return (true);
}