Modified <ListWidget> rendering logic to use item ID rather than arra…

…y index as the React key for the items listing, as an item's array index can change, while the ID will remain constant throughout its lifetime.

webpack_in/entry.jsx

@@ -109,7 +109,7 @@ class ListWidget extends React.Component {
             <div style={ objStyleCommon }>
               <div style={ objStyleContent }>
                 <ul style={{ display: 'inline-block', textAlign: 'left' }}>
-                  { this.state.items.map((objItem, index) => (<li key={ index }>
+                  { this.state.items.map((objItem, index) => (<li key={ objItem.id }>
                                                                 { objItem.caption }
                                                               </li>)) }
                 </ul>