Hello Su Pei,
This is expected behaviour and it can be observed in most of the Spreadsheet editors.
I can confirm that Excel will give the option to either fill the series or copy the values, but this feature is currently not supported.
I can suggest submitting a feature request in our UserVoice portal and based on its popularity we may implement it in a future release:
On the other hand, I would like to present you an offering that may be relevant and applicable to your needs - our Feature Acceleration program. It allows a customer to negotiate certain components or functionality to be implemented on demand or sooner than our roadmap implies. Feature acceleration fits well in scenarios where a feature or enhancement is important for an application's success, but it is not planned to be available at the time of the application's completion.
Let us know if you are interested in pursuing this option at any time and I will arrange for our Professional Services team to get in touch with you to discuss your exact requirements and possible timeframes.
Telerik by Progress
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