Hi Jay,
Yes, the
OnClientShowing property of the
RadContextMenu "Prometheus" control denotes the
onshowing event of the client object to which you can attach a javascript function to be executed.
Please, find attached an example page I just created.
By the way, if by any chance are referring to
RadMenu "Classic", you should use its
OnClientContextShowing property.
I hope this helps.
Best regards,
Erjan Gavalji
the Telerik team