The Direct2D rendering options is available for WPF only. The mentioned article should not be visible in the Silverlight documentation and it must be removed. Please, accept our apologies for any inconvenience it might have caused you. As a token of gratitude for your involvement in identifying and reporting this issue I updated your Telerik points.
Meanwhile, if you have any additional questions or concerns regarding Telerik controls, please do not hesitate to contact us.
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