@Override
		public void handleEvent (Event e) {
			String string = e.text;
			char [] chars = new char [string.length ()];
			string.getChars (0, chars.length, chars, 0);
			for (int i=0; i<chars.length; i++) {
				if (!('0' <= chars [i] && chars [i] <= '9')) {
					e.doit = false;
					return;
				}
			}
		}