Wow. Thanks for the tip.
It doesn't work in VB. Issue here is that Facebook.Web.CanvasIFrameBasePage has two properties named api.
public string Api
public API API
Since VB is not case sensitive, it tells me it's an ambiguous property.
I couldn't see either Api or API in object browser in a VB project. But I could in reflector and in object browser in a C# project.
After opening the source and changing one of the property names in the CanvasIFrameBasePage class, it compiles ok.