title: Making only one column of a QTreeWidgetItem editable
body: <p>I have a <code>QTreeWidgetItem</code> with two columns of data, is there any way to make only the second column editable? When I do the following:</p>
  
  <pre><code>QTreeWidgetItem* item = new QTreeWidgetItem();
  item-&gt;setFlags(item-&gt;flags() | Qt::ItemIsEditable);
  </code></pre>
  
  <p>all columns become editable. </p>