In order to implement the behavior you can use the following approach.
- add GridButtonColumn and set its CommandName to Select
- handle the ItemCommand event of the RadGrid
- check what command raised the event and if it was Select get the values from the current row
- populate the TextBox controls with the relevant values
If you would like additional information on how you can access the values in the cells of the grid you would find the following article interesting.
For convenience I am attaching a sample project where the behavior is implemented.
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