def _on_mouse_moved(self, event):
        """ mouse moved callback """
        if event.modifiers() & Qt.ControlModifier:
            self._select_word_under_mouse_cursor()
        else:
            self._remove_decoration()
            self.editor.set_mouse_cursor(Qt.IBeamCursor)
            self._previous_cursor_start = -1
            self._previous_cursor_end = -1