Thank you for your feedback.
This warning looks for xaml usages only, we don't analyze backend usages with ResourceDictionary["key"].
I was creating a storyboard placeholder in the XAML that I then populated and manipulated in code-behind.
This seems to be a widely used approach, so if you don't want to see that warning you can simply turn it off from the options.
If you have any other problems or suggestions, please don't hesitate to write back.
the Telerik team
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