code: def apply_panes_settings(self):
          
          for plugin in (self.widgetlist + self.thirdparty_plugins):
              features = plugin.FEATURES
              if CONF.get('main', 'vertical_dockwidget_titlebars'):
                  features = features | QDockWidget.DockWidgetVerticalTitleBar
              plugin.dockwidget.setFeatures(features)
              plugin.update_margins()
docs: Update dockwidgets features settings