title: how can i delete all items under selected item in treeview
body: <p>i have treeview as the view and QStandardItemModel as the model.
  now i each node in the model has child nodes . my question is
  how can i delete all the child nodes under selected item ?
  all i found is this but this is for one row . i need all the rows under item.</p>
  
  <pre><code>bool TableModel::removeRows(int position, int rows, const QModelIndex &amp;parent)
  {
      beginRemoveRows(parent, position, position + rows - 1);
  
      for (int row = 0; row &lt; rows; ++row) {
          rowList.removeAt(position);
      }
  
      endRemoveRows();
      return true;
  }
  </code></pre>