title: How to use QFileDialog::getsaveFileName to save a ui file with QFormBuilder?
body: <p>What I want:</p>
  
  <p>When I call save(), I would like to use the QFileDialog to get the file, and save ui file with QFormBuilder(because it lets me save ui files recognizable by Qdesigner)</p>
  
  <p>What I have:</p>
  
  <p>I have a method called save()</p>
  
  <pre><code>void MainWindow::save()
  {
      QString savef = QFileDialog::getSaveFileName(this, tr("Save"), "file", tr("UI files (*.ui)"));
      //here down I would like to use the savef to save ui file
      QFormbuilder builder;
      builder.save(savef, myui);
  
  } 
  </code></pre>
  
  <p>But savef is not QIODevice, and the Qt is complaining about it. </p>
  
  <p>Any idea how I can do it? </p>
  
  <p>Thanks. </p>