title: Unable to have more than 2 columns in staggeredGridView
body: <p>So I am building a sort of image search and I need to display the images in a staggeredGridView since the images can be of different sizes. I have tried using StaggeredGridView.count, builder, countBuilder, extent but just cannot understand how to do it. In the builder, I cannot get more than 2 columns even though there is plenty of space for more. Here is the code I have tried (I have tried tons of different types as I mentioned above but this is what I tried last)</p>
  <pre><code>Container(
          width: constraints.maxWidth,
          height: constraints.maxHeight - 72,
          child: StaggeredGridView.countBuilder(
            crossAxisCount: 3,
            padding: EdgeInsets.all(2.0),
            staggeredTileBuilder: (int index) =&gt; new StaggeredTile.fit(2),
            mainAxisSpacing: 4.0,
            crossAxisSpacing: 4.0,
            itemCount: webPage['images_results'].length,
            itemBuilder: (BuildContext context, int index) {
              return Container(
                child: InkWell(
                  onTap: () {},
                  child: Column(children: &lt;Widget&gt;[
                    Image(
                      width: constraints.maxWidth * 0.2,
                      image: NetworkImage(
                          webPage['images_results'][index]['thumbnail']),
                      // placeholder: AssetImage('assets/Loading.gif'),
                    ),
                    SizedBox(
                      height: 1,
                    ),
                    Container(
                      width: constraints.maxWidth * 0.2,
                      child: Text(webPage['images_results'][index]['title'],
                          style: style1.copyWith(color: text2, fontSize: 16)),
                    ),
                    SizedBox(
                      height: 1,
                    ),
                    Text(webPage['images_results'][index]['source'],
                        style: style1.copyWith(color: text3, fontSize: 10)),
                  ]),
                ),
              );
            },
          ))
  </code></pre>
  <p>Expected Output
  <a href="https://i.stack.imgur.com/Cjsf1.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Cjsf1.jpg" alt="" /></a></p>
  <p>Current Output
  <a href="https://i.stack.imgur.com/LPUdA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LPUdA.png" alt="enter image description here" /></a>
  Any help would be appreciated. Please let me know if anymore code is needed</p>
  <p><strong>Using Wrap Output</strong>
  <a href="https://i.stack.imgur.com/BSUs2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BSUs2.jpg" alt="enter image description here" /></a></p>