[CONNECT C++] DgnButtonEvent not found?

I'm trying to use Bentley::DgnPlatForm::DgnButtonEvent as a parameter to a function but the compiler says type 'Bentley::DgnPlatform::DgnButtonEvent' is undefined.

UpdatePosition(Bentley::DgnPlatform::DgnButtonEvent ev ) {}

I've included DgnPlatform.h and also added "using namespace Bentley::DgnPlatform: in my code module. When I look at DgnPlatform.h, all I see for the definition is:

DGNPLATFORM_TYPEDEFS (DgnButtonEvent)

so, I'm not sure if it really exists or not...

Bruce