title: Filtering executable files in QFileDialog on Linux
body: <p>I am trying to make a file picker to select a program (executable file).</p>
  
  <p>My understanding of the documentation for QDir and QFileDialog is that the following should show a file dialog with only executable files. However, it shows no files at all (and no directories either) even though there are executable files in the directory.</p>
  
  <pre><code>    self.browseDialog = QtGui.QFileDialog()
      self.browseDialog.setFilter(QtCore.QDir.Executable | QtCore.QDir.Files)
      self.browseDialog.exec_()
  </code></pre>
  
  <p>Am I doing something wrong? Can this be achieved? I would also like to do something a little more complex: show files that are executable <em>or</em> end with certain extensions.</p>
  
  <p>I am using PyQt 4.7.4 on Ubuntu Maverick.</p>