i think it is lack of adab to do so specially in front of rawDah mubarak of the beloved prophet a'laihi afDalus salat wat-tasleem. We know that sah'abah used to sit in his presence as if birds were sitting on their heads; therefore, how it would be permissible to do these exra activities. besides, though i should not blame anyone, sometime it may lead to show off while person may not realize it. i have too done it several times but not in front of the blessed fence, often many meters away out side the masjid sharif or beside the wall near to baqi'y sharif. but, still a dear brother, who i called from there, forbade me to do so, and i think he was right.