Hi Marc Roussel,
By the looks of it, it seems you have managed to solve the original issue.
As for the suggestion you are making - I cannot say it is not a valid one. We do have some concerns about it though. Think of all the states a grid row can be in (Normal, MouseOver, Selected, Invalid, Edit) multiply that by the number of elements (BorderBrush, Background, Foreground to name a few) and we have created a monster right there. :)
In no way does this mean we are not thinking about improving on the styling experience, we are just looking at the best way to do it.
If there is anything I can help you with in your styling efforts - let me know.
the Telerik team
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