D2DERR_* are HRESULTs (LONG) but wind up being unsigned.
widl does not support acf option
I had found that constant, yes, but https://msdn.microsoft.com/en-us/library/windows/desktop/ms683200(v=vs.85).aspx states the following: If dwFlags contains GET_MODULE_HANDLE_EX_UNCHANGED_REFCOUNT, this function must be used carefully in a multithreaded application. There is no guarantee that the module handle remains valid between the time this function returns the handle and the time it is used. For example, a thread retrieves a module handle, but before it uses the handle, a second thread frees...
MinGW is missing CD3D11_DEPTH_STENCIL_DESC
MinGW is Missing GET_MODULE_HANDLE_EX_UNCHANGED_REFCOUNT Constant
StringCchPrintfW errors
I believe this is fixed with https://sourceforge.net/p/mingw-w64/mingw-w64/ci/d79862083e8b5f8a09f4301da218ddc59ce62c64/
This can be closed