function preloadimg(){
			nouvellesRoll = new Image();
			nouvellesRoll.src = "_images/bt_nouvelles_on.jpg";
			GroupeRoll = new Image();
			GroupeRoll.src = "_images/bt_groupe_on.jpg";
			SpectaclesRoll = new Image();
			SpectaclesRoll.src = "_images/bt_spectacles_on.jpg";
			SpectaclesRoll = new Image();
			SpectaclesRoll.src = "_images/bt_spectacles_on.jpg";
			MediasRoll = new Image();
			MediasRoll.src = "_images/bt_medias_on.jpg";
			LiensRoll = new Image();
			LiensRoll.src = "_images/bt_liens_on.jpg";
			}