docs: def _on_dirty_changed(self, dirty):
          """
          Adds a star in front of a dirtt tab and emits dirty_changed.
          """
          try:
              title = self._current._tab_name
              index = self.indexOf(self._current)
              if dirty:
                  self.setTabText(index, "* " + title)
              else:
                  self.setTabText(index, title)
          except AttributeError:
              pass
          self.dirty_changed.emit(dirty)