code: def _onShortcutSelectAndScroll(self, down):
          
          cursor = self.textCursor()
          cursor.movePosition(QTextCursor.Down if down else QTextCursor.Up, QTextCursor.KeepAnchor)
          self.setTextCursor(cursor)
          self._onShortcutScroll(down)
docs: Ctrl+Shift+Up/Down pressed.
          Select line and scroll viewport