title: How to work with signals from QTableWidget cell with cellWidget set
body: <p>I've got a <code>QTableWidget</code> with some columns inside.
  <br>Due to my needs I set <code>QComboBox</code> inside some columns and fill them with necessary data.</p>
  
  <pre><code>void settingsDialog::onAddFieldButtonClicked()
  {
      fieldsTable-&gt;setRowCount(++rowCount);
      combo = new QComboBox();
      combo-&gt;addItem(QString("Choose from list..."));
      foreach( int height, heightsAvailable)
          combo-&gt;addItem(QString("%1").arg(height));
      fieldsTable-&gt;setCellWidget(rowCount-1, 3, combo);
      // etc for other columns ...
  }
  </code></pre>
  
  <p>The question is how to catch signals from these combo boxes if they were changed?
  <br>I want to know <code>row</code> and <code>col</code> of changed widget (combo box) and the value which was set.</p>
  
  <p><br> I've tried all available signals which are mentioned in Qt docs for <code>QTableWidget</code>, but they work only if cell doesn't have widget inside it.
  <br> Is there a simple and Qt-way to get what I need?</p>