In Microsoft Xaml thickness properties can be expressed either with spaces or with commas. These two Xaml values have the same result:
The Noesis implementation does not support the second option, with space separators. I don't think this is a big deal. But, it's important to call this out in the documentation somewhere if this is intended. (It may be in the docs and I may have missed it too )

Thanks to point that out.
We will include that case in the Thickness parser.