React: handle changes only when editing

Fixes #1405

examples/react/js/todoItem.jsx

@@ -37,7 +37,9 @@ var app = app || {};
 		},
 
 		handleChange: function (event) {
+			if (this.props.editing) {
 				this.setState({editText: event.target.value});
+			}
 		},
 
 		getInitialState: function () {