CreateWindowEx failing

Question

Could the fact that you're requesting fullscreen be causing a problem? w = new cog::Window(100, 100, 16, TRUE);

If it helps, this works in my code base:

HWND impl::window_impl::create_window_(
    window_impl* window // associated window object
) {
    auto const INSTANCE = ::GetModuleHandleW(L"");

    WNDCLASSEXW const wc = {
        sizeof(WNDCLASSEXW),
        CS_OWNDC | CS_HREDRAW | CS_VREDRAW,
        window_impl::top_level_wnd_proc_,
        0,
        0,
        INSTANCE,
        nullptr,
        ::LoadCursorW(nullptr, MAKEINTRESOURCE(IDC_ARROW)),
        nullptr,
        nullptr,
        CLASS_NAME,
        nullptr
    };

    ::RegisterClassExW(&wc); // ignore return value

    auto const result = ::CreateWindowExW(
        0,
        CLASS_NAME,
        L"window",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        CW_USEDEFAULT, CW_USEDEFAULT,
        (HWND)nullptr ,
        (HMENU)nullptr,
        INSTANCE,
        window
    );

    return result;
}

[edit] I think your call to CreateWindowExW has the params in the wrong order -- specifically the instance paramater. Do you compile with STRICT on? It should detect this kind of problem.

[edit] Not directly related, but your implementation won't work when compiled as 64bit code, and it doesn't check for possible errors -- you should use something like:

//--------------------------------------------------------------------------
//! Get the userdata for the window given by @c hwnd (our window object).
//! @throw bklib::platform::windows_exception
//--------------------------------------------------------------------------
impl::window_impl* get_window_ptr(HWND hwnd) {
    ::SetLastError(0);
    auto const result = ::GetWindowLongPtrW(hwnd, GWLP_USERDATA);

    if (result == 0) {
        auto const e = ::GetLastError();
        if (e) {
            BOOST_THROW_EXCEPTION(bklib::platform::windows_exception()
                << bklib::platform::windows_error_code(e)
            );
        }
    }

    return reinterpret_cast<impl::window_impl*>(result);
}

//--------------------------------------------------------------------------
//! Set the userdata for the window given by @c hwnd to be our
//! window object.
//! @throw bklib::platform::windows_exception
//--------------------------------------------------------------------------
void set_window_ptr(HWND hwnd, impl::window_impl* ptr) {
    ::SetLastError(0);
    auto const result = ::SetWindowLongPtrW(hwnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(ptr));

    if (result == 0) {
        auto const e = ::GetLastError();
        if (e) {
            BOOST_THROW_EXCEPTION(bklib::platform::windows_exception()
                << bklib::platform::windows_error_code(e)
            );
        }
    }
}

[edit] More code in case it helps

//------------------------------------------------------------------------------
//! Top level window procedure which forwards messages to the appropriate
//! impl::window_impl instance.
//! @throw noexcept
//!     Swallows all exceptions at the API boundary.
//------------------------------------------------------------------------------
LRESULT CALLBACK impl::window_impl::top_level_wnd_proc_(
    HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam
) try {
    // set the instance pointer for the window given by hwnd if it was just created
    if (msg == WM_NCCREATE) {
        auto const cs =
            reinterpret_cast<CREATESTRUCTW const*>(lParam);
        auto const window_ptr =
            reinterpret_cast<window_impl*>(cs->lpCreateParams);

        set_window_ptr(hwnd, window_ptr);
    }

    // the window object to forward the message to
    auto const window = get_window_ptr(hwnd);

    if (window) {
        return window->window_proc_(hwnd, msg, wParam, lParam);
    } else {
        // it's possible we will receive some messages beofre WM_NCCREATE;
        // use the default handler
        return ::DefWindowProcW(hwnd, msg, wParam, lParam);
    }
} catch (std::exception&) {
    ::PostQuitMessage(-1);
    return 0;
} catch (...) {
    ::PostQuitMessage(-1);
    return 0;
}

//------------------------------------------------------------------------------
//! Called by the top level window proc. Dispatches messages to their
//! appropriate handler function.
//------------------------------------------------------------------------------
LRESULT impl::window_impl::window_proc_(
    HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam
) {
    return ::DefWindowProcW(hwnd, msg, wParam, lParam);
}

//------------------------------------------------------------------------------
void impl::window_impl::create() {
    handle_ = create_window_(this);
}

//------------------------------------------------------------------------------
void impl::window_impl::show(bool visible) {
    ::ShowWindow(handle_, SW_SHOWDEFAULT);
    ::InvalidateRect(handle_, nullptr, FALSE);
    ::UpdateWindow(handle_);
}