If I pin a member of a garbage collected structure, can I safely assume
that the entire struct is pinned?

I use something like that: (new whidbey syntax, but that shouldn't make
a difference):

[StructLayout(LayoutKind::Sequential)]
public ref struct MyStruct {
Int32  memberA;
Int16  memberB;
Int32  memberC;
}
...

MyStruct^ struct = gcnew MyStruct();
void* pData = somedata_somwhere;

//pData points to a memory location,
//that holds data not only about
//memberA but also memberB and memberC

pin_ptr<int> pMemberA = &struct->membera;
memcpy((void*)pMemberA, pData, sizeofdata);
pMemberA = nullptr;

it works but is it correct?
Would it also be correct if i hadn't specified LayoutKind::Sequential?

Thanks
Ben