title: how to show progress dialog with Gtk# while loading data?
body: <p>I have main window with button "open file". On clicking file selector dialog shows up and then file is loaded. I would like to show progress dialog while loading the data. However when I call Run</p>
  
  <pre><code>dlg.Run();
  load_data(); // not executed
  </code></pre>
  
  <p>the execution stops there (I have to close the dialog to load the data), if I call Show</p>
  
  <pre><code>dlg.Show();
  load_data();
  </code></pre>
  
  <p>then loading is done, but the dialog does not show up.</p>
  
  <p>So, how to show modal, progress dialog and in meantime load the data?</p>
  
  <p>Note: this question is only about showing the progress dialog, NOT updating the progressbar widget.</p>