title: smartgwt listgridfield with boolean type with checkbox in field header
body: <p>I've listgridfield in which I need to show checkboxes. So, I just set that field like</p>
  
  <pre><code>listGridFieldChk.setFieldDataType(ListGridFieldType.BOOLEAN);
  </code></pre>
  
  <p>It working fine like I want, only thing which I need now is checkbox in header with the same field. So when user want to check or uncheck all checkbox at once will do with this.</p>
  
  <p><img src="https://i.stack.imgur.com/VhsFW.jpg" alt="enter image description here"></p>
  
  <p>I know about the listGrid property which put checkbox field at first column</p>
  
  <pre><code>thisGrid.setSelectionAppearance(SelectionAppearance.CHECKBOX);
  </code></pre>
  
  <p>But this will not helpful for me, I need it at custom level.</p>