I think the issue is that the support for .NET libraries on Mono is trailing what is delivered with the MSFT tools. That said, Mono has been doing a generally

I think the issue is that the support for .NET libraries on Mono is trailing what is delivered with the MSFT tools. That said, Mono has been doing a generally good job trying to keep up and has very visible api pages about what is/isn't supported and how people can contribute.