Thank you for writing.
You can achieve this behavior by changing the editor type and using a RadDropDownListEditor
. The following section in our documentation provides an overview of the different editors also shows how they can be customized: RadGridView | Editors
I am also sending you attached a sample project demonstrating the suggested approach as well as a short video showing the result on my end.
I hope this helps. Should you have further questions please do not hesitate to write back.
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