The problem comes from the fact that the Visual Cue in OOB is rendered in completely different way than in Silverlight. We are using a Window for showing Visual Cue but in OOB this Window can not be set as transparent and hence the white border behind around the payload. There should be a way to fix this by modifying the Drag Cue style however the issue seems to be more complex than we thought. We will need some more time to investigate how we can fix this bad behavior or provide a workaround with a Drag Cue style or else.
We will investigate the issue further next week and I will follow up this thread and the one below with our findings.
the Telerik team
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