code: def _selectLines(self, startBlockNumber, endBlockNumber):
          
          startBlock = self.document().findBlockByNumber(startBlockNumber)
          endBlock = self.document().findBlockByNumber(endBlockNumber)
          cursor = QTextCursor(startBlock)
          cursor.setPosition(endBlock.position(), QTextCursor.KeepAnchor)
          cursor.movePosition(QTextCursor.EndOfBlock, QTextCursor.KeepAnchor)
          self.setTextCursor(cursor)
docs: Select whole lines