My next thought was "Have I somehow referenced the wrong version of TinyCore?" So I checked and this was the path:
C:\Program Files (x86)\Microsoft .NET Micro Framework\v4.2\Assemblies\le\Microsoft.SPOT.TinyCore.dll
I can work around it; I really only wanted EventHandler, which isn't hard to replicate.
Nevertheless, has anyone else experienced this?
Never mind. Even though site search turned up nothing, google found another identical post on this site - apparently TinyCore is mostly about WPF and is not really supported on N+.
Let's therefore revise the question.
Chris can we pull out the useful parts of TinyCore such as the definition of EventHandler? I have to keep qualifying my own definition of EventHandler otherwise the compiler claims it's ambiguous with the definition from TinyCore (though how the hell it knows that without a TinyCore reference is beyond me).
I used a different name with the same signature:
public delegate StallEventHandler(object sender, EventArgs e);
No need to qualify the name, no need to import TinyCore.