title: How to add a checkbox column to existing gridview columns in yii2?
body: <p>I want to add a column to gridview but I don't want to list all of columns(because there are some columns as default).
  I know that I can add a column by follow:</p>
  
  <pre><code>$widget = Yii::createObject([
      'class' =&gt; 'yii\grid\GridView',
      'dataProvider' =&gt; $dataProvider,
      'columns' =&gt; [
          'col1',
          'col2',
          'class' =&gt; 'yii\grid\CheckboxColumn',
      ]
  ]);
  </code></pre>
  
  <p>but I don't want to list all default columns and just add a checkbox column. like follow:</p>
  
  <pre><code>$widget = Yii::createObject([
      'class' =&gt; 'yii\grid\GridView',
      'dataProvider' =&gt; $dataProvider,
      'columns' =&gt; [
          'class' =&gt; 'yii\grid\CheckboxColumn',
      ]
  ]);
  </code></pre>
  
  <p>Then it will be displayed at the end of default columns.
  How can I do it?</p>