As I mentioned in the previous response, determine the selected items
events is not suitable for your scenario, because they are useful when the SelectionMode
is set to "Single".
I could suggest you to use Checkboxes
feature of the RadListBox
control in order to implement the desired functionality. Thus you could easily determine the client's choice with the help of the server-side event OnItemCheck
and populate the second RadListBox
based on previous selection. In addition, this is a common and user-friendly way to achieve the desired functionality.
the Telerik team
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