title: limit directory traversal in QFileDialog
body: <p>I'm using QFileDialog to select a directory. I'm having an issue that I'm unable to resolve. I've spent a lot of time googling for this but have come up with zilch.</p>
  
  <p>I specify the starting directory (say /home/dhoti/downloads) and I want to disable navigation above this directory. For example the user should not be allowed to go to /home/dhoti or /tmp etc. How do I achieve this?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>QFileDialog dlg(this, "Select Firmware Version");
  dlg.setDirectory("/home/dhoti/downloads");
  dlg.setFileMode(QFileDialog::DirectoryOnly);
  dlg.setOption(QFileDialog::ReadOnly, true);
  dlg.setOption(QFileDialog::HideNameFilterDetails, true);
  dlg.setViewMode(QFileDialog::List);
  dlg.setAcceptMode(QFileDialog::AcceptOpen);
  dlg.exec();
  qDebug() &lt;&lt; "selected files: " &lt;&lt; dlg.selectedFiles();
  </code></pre>
  
  <p>thanks for any help
  Dhoti</p>