title: Flutter Dismissible not removing from tree
body: <p>I am working with Flutter and am struggling to remove a Dismissible object from the tree. Below is my code. I have created a custom class that is stored in the list 'newlist.' I seemingly remove the Dismissible object from the List and setState(), but it does not seem to work. Any help is greatly appreciated.</p>
  
  <pre><code>   return new Dismissible(key: new Key("newlist"),
  direction: DismissDirection.horizontal,
  onDismissed: (DismissDirection direction) {
              setState(() {
                newlist.remove(newlist[index]);
                print(newlist.length);
  
              });
  },
  child: new ListTile(
  leading: const
  Icon(Icons.album),
  title: new Text(newlist[index].amount),
  subtitle: new Text(
  newlist[index].name)));
  })),
  </code></pre>