MFC message only invisible window

gistfile1.cpp

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch(msg) {
	case WM_CLOSE:
		DestroyWindow(hWnd);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, msg, wParam, lParam);
	}
	return 0;
}
 
HWND CreateMessageOnlyWindow(HINSTANCE hInstance)
{
	WNDCLASSEX wx = {};
	wx.cbSize = sizeof(WNDCLASSEX);
	wx.lpfnWndProc = WndProc;
	wx.hInstance = hInstance;
	wx.lpszClassName = L"Message-Only Window";
	wx.style=0;
	wx.cbClsExtra = wx.cbWndExtra = 0;
	wx.hIcon = NULL;
	wx.hCursor = NULL;
	wx.hbrBackground = NULL;
	wx.lpszMenuName = NULL;
	wx.hIconSm=NULL;
 
	if ( RegisterClassEx(&wx) )
		return CreateWindow(L"Message-Only Window", NULL, 0, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, HWND_MESSAGE, NULL, NULL,  NULL);
	else
		return NULL;
}