title: Flutter GridView footer (for indicating load with infinite scrolling)
body: <p>I have a GridView which works pretty smooth. I use the grid in the context of infinite scrolling where more items are loaded via a REST API whenever scrolling is close to the bottom. No problems here.</p>
  
  <p>However I want to be able to display a loading indicator at the bottom of the grid. This Widget <strong>should span all columns in the grid</strong>, but should still be a part of the scrollable content.</p>
  
  <p>I am new to Flutter and lost as how to achieve this.</p>
  
  <p>My (working) GridView is instantiated like so:</p>
  
  <pre><code>return new GridView.builder(
    gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: _COLUMN_COUNT),
    controller: widget.scrollController,
    itemCount: widget.items.length,
    itemBuilder: (BuildContext context, int index) {
      return new _ItemView(item: widget.items[index]);
    },
  );
  </code></pre>