title: Qt QProgressBar indeterminate
body: <p>My application needs to do some operations which might take a second but might also take 10 minutes. For this purpose I need to show a QProgressDialog with indeterminate QProgressBar during the operation.</p>
  
  <pre><code>QProgressDialog dlg( this );
  dlg.setBar( new QProgressBar() );
  dlg-&gt;setMaximum( 0 );
  dlg-&gt;setMinimum( 0 );
  dlg.setModal( true );
  dlg.show();
  
  //operation ...
  
  dlg.close();
  </code></pre>
  
  <p>During my operation the dialog shows up, <strong>is transparent, has no progressbar</strong> and after the operation it closes. </p>
  
  <p>Does anyone know what I can do to show a modal dialog which prevents the user from interacting with the application and which shows the user an indeterminate progressbar?</p>