Further investigation turned out that this must be a bug. The binding that the propertygrid's DescriptorPropertyDefinition is doing does not set a converterCulture. So it's null and always the default culture settings are used for the implicit wpf converters.
I created Issue https://wpftoolkit.codeplex.com/workitem/21909 for it.
regards
Andreas
I created Issue https://wpftoolkit.codeplex.com/workitem/21909 for it.
regards
Andreas