function setTClass (obj,cname) {
		obj.setAttribute("className",cname);
		obj.setAttribute("class",cname);
	}
	
		function setimg(num) {
			var img1 = document.getElementById('img1');
			var img2 = document.getElementById('img2');
			var img3 = document.getElementById('img3');
			var mainimg = document.getElementById('mainimgsrc');
			switch (num) {
				case 2:
				mainimg.src = 'images/mon_image2.jpg';
				setTClass(img1,'imgbanneroff');
				setTClass(img2,'imgbanneron');
				setTClass(img3,'imgbanneroff');
				break
				case 3:
				mainimg.src = 'images/mon_image3.jpg';
				setTClass(img1,'imgbanneroff');
				setTClass(img2,'imgbanneroff');
				setTClass(img3,'imgbanneron');
				break
				case 1:
				default:
				mainimg.src = 'images/mon_image1.jpg';
				setTClass(img1,'imgbanneron');
				setTClass(img2,'imgbanneroff');
				setTClass(img3,'imgbanneroff');
				break
			}
		}