NS_NOTYETIMPLEMENTED("write me!"); return NS_ERROR_NOT_IMPLEMENTED;
NS_PRECONDITION(aLastChild != nsnull, "null ptr"); if (! aLastChild) return NS_ERROR_NULL_POINTER;  if (mRootContent) { return mRootContent->QueryInterface(nsIDOMNode::GetIID(), (void**) aLastChild); } else { *aLastChild = nsnull; return NS_OK; }
XULDocumentImpl::GetLastChild(nsIDOMNode** aLastChild){    NS_NOTYETIMPLEMENTED("write me!");    return NS_ERROR_NOT_IMPLEMENTED;}