code: def setupDock(self):
          
          self.dock = QtWidgets.QDockWidget("Classes", self)
          self.dock.setWidget(self.tree)
          self.dock.setFeatures(QtWidgets.QDockWidget.NoDockWidgetFeatures)
          self.addDockWidget(QtCore.Qt.LeftDockWidgetArea, self.dock)
docs: Setup empty Dock at startup.