title: How to display parent directory in tree view?
body: <p>In my application I have a QTreeview. I have a folder named "test" that contains many subfolders. The treeview only shows the subfolders not the test forlder it self!</p>
  
  <pre><code>def create_treeview(self):
      self.treeView = QTreeView()
      self.treeView.setMinimumSize(QSize(250, 0))
      self.treeView.setMaximumSize(QSize(250, 16777215))
      self.treeView.setObjectName("treeView")
  
      self.dirModel = QFileSystemModel()
      self.dirModel.setRootPath(QDir.rootPath())
      self.dirModel.setFilter(QDir.NoDotAndDotDot | QDir.AllDirs)
  
      self.treeView.setModel(self.dirModel)
      self.treeView.setRootIndex(self.dirModel.index("/home/data/test"))
      self.treeView.setHeaderHidden(True)
      self.treeView.clicked.connect(self.tree_click)
      return self.treeView
  </code></pre>