docs: def _on_mouse_moved(self, event):
          """ mouse moved callback """
          if event.modifiers() & QtCore.Qt.ControlModifier:
              cursor = TextHelper(self.editor).word_under_mouse_cursor()
              if (not self._cursor or
                      cursor.position() != self._cursor.position()):
                  self._check_word_cursor(cursor)
              self._cursor = cursor
          else:
              self._cursor = None
              self._clear_selection()