docs: def _on_key_press(self, widget, event):
          """Updates the currently pressed keys
  
          In addition, the sidebars are toggled if <Ctrl><Tab> is pressed.
  
          :param Gtk.Widget widget: The main window
          :param Gdk.Event event: The key press event
          """
          self.currently_pressed_keys.add(event.keyval)
          if event.keyval in [Gdk.KEY_Tab, Gdk.KEY_ISO_Left_Tab] and event.state & Gdk.ModifierType.CONTROL_MASK:
              self.toggle_sidebars()