RadTreeView supports both client- and server-side validation. By setting the CausesValidation property to True/False you can control whether the treeview should perform validation before posting back to the server.
If you are using client-side validation (JavaScript) the treeview will not postback unless all form controls on the page match the conditions of their respective validators.
In case you are using server-side validation, you can safely use Page.IsValid after the treeview postback event.
You can disable validation by setting CausesValidation to False.
See Also