Hab ein Problem mit dem Anzeigen eines Buttons als Child-Window. Das Hauptfenster erscheint zwar, aber der Button wird scheinbar nicht erstellt.

[...]

ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX); 

	wcex.style			= CS_HREDRAW | CS_VREDRAW;//CS_OWNDC
	wcex.lpfnWndProc	= (WNDPROC)WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= LoadIcon(hInstance, (LPCTSTR)IDI_TEST4);
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.lpszMenuName	= (LPCSTR)IDC_TEST4;
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);

	return RegisterClassEx(&wcex);
}

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

	if (!hWnd)
	{
		return FALSE;
	}

	ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	int wmId, wmEvent;
	TCHAR szHello[MAX_LOADSTRING];
	LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);
	HWND hButton;

	switch (message) 
	{
		case WM_CREATE:
			{
			hButton = CreateWindow(  "button",
									"Knopf",
									WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
									0, 0, 0, 0,
									hWnd,
									NULL,
									((LPCREATESTRUCT) lParam) -> hInstance,
									NULL);
			return 0 ;
			}

[...]

CreateWindow(  "button",
               "Knopf",
               WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
               0, 0, 100, 100, // <--- Werte für die Größe geändert
               hWnd,
               NULL,
               ((LPCREATESTRUCT) lParam) -> hInstance,
               NULL);