function imgOn(imgName) {
		if (document.images) {
			if (document[imgName] == null) {
				document[imgName] = new Image();
			}
			document[imgName].src="selon.gif";
		}
	}

	function imgOff(imgName) {
		if (document.images) {
			if (document[imgName] == null) {
				document[imgName] = new Image();
			}
			document[imgName].src="seloff.gif";
		}
	}
	function setTopic(imgName) {
		if (document.images) {
			if (document[imgName] == null) {
				document[imgName] = new Image();
			}
			document["topic"].src=imgName + ".jpg";
		}
	}