It behaves entirely different to the standard textbox!
I drag a telerik textbox onto a webform and also a standard textbox.
I drag a requiredfieldvalidator onto the form and set it's controltovalidate property to the telerik textbox.
When I mouse into and out of the telerik textbox the validator fires (incorrectly).
When I set the controltovalidate property of the validator to the standard textbox and mouse into and out of that textbox, the validator doesn't fire (as by design). When you click the submit button, the validator fires, correctly.
Hence, there is a bug in the telerik control.
<
asp:ScriptManager ID="ScriptManager1" runat="server" />
<
telerik:RadTextBox ID="tt" runat="server" />
<
asp:TextBox id="ms" runat="server" />
<
asp:RequiredFieldValidator id="rfv" runat="server" ControlToValidate="tt" ErrorMessage="*" />
<
asp:Button ID="btn" runat="server" Text="go" />