The difference is that the backend login form is hosted by the token
issuer and you are submitting credentials in order to receive a token
and the redirect_uri is telling the issuer where to send this token.
However the widget is getting a token from the issuer using ajax, and
does not care about the redirect - after the token was received it is
submitted to the current page.
Unfortunately there is no option at the moment to change the redirec_uri
behaviour. Still we are considering the addition of such functionality
for one of our upcoming releases. I am sorry about the caused
the Telerik team
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