[nonVCL] Screensaver mit Preview (Template) - Problem

[turboPASCAL]

Moin,

folgendes Problem, das Preview wird zwar angezeigt aber nicht in dem dafür vorgesehene Fenster.
Das Handle für das Previewfenster wird von Win per Parameter an den zu startenden Scrsaver übergeben.

Code:

Test.EXE /p 4711

Ich finde den Fehler nicht.

Der Hauptteil:

Delphi-Quellcode:

function WndProc(hWnd: HWND; uMsg: UINT; wParam: wParam; lParam: LParam):
  lResult; stdcall;
begin
  Result := 0;

  case uMsg of
    WM_CREATE:
      begin
        if ScreenMode = scrmStart then ShowCursor(FALSE);
        SetTimer(hWnd, 1, 100, nil);
      end;
    WM_DESTROY:
      begin
        if ScreenMode = scrmStart then ShowCursor(TRUE);
        KillTimer(hWnd, 1);
        DestroyWindow(hWnd);
        PostQuitMessage(0);
      end;
    WM_ACTIVATE:
      if (wParam = Integer(FALSE)) then
        PostMessage(hWnd, WM_CLOSE, 0, 0); // terminates the screen saver.

    WM_LBUTTONDOWN,
    WM_MBUTTONDOWN,
    WM_RBUTTONDOWN,
    WM_KEYDOWN:
      begin
        if ScreenMode = scrmStart then
          PostMessage(hWnd, WM_CLOSE, 0, 0);
      end;

    // Wird verwendet um den Start des Bildschirmschoners zu verhindern
    // zB. wenn eine App. den Bildschirmsch. unterdrücken will
    SC_SCREENSAVE,
    SC_CLOSE: Result := 0;

    WM_TIMER:
      begin
        OnTimerEvent(hWnd);
      end;
  else
    Result := DefWindowProc(hWnd, uMsg, wParam, lParam);
  end;
end;

BEGIN
  InitCommonControls; // Wegen XPManifest in der Res.

  // Comandline auswerten
  if (ParamStr(1) + #32)[1] in ['-', '/'] then
  begin
    case (ParamStr(1))[2] of
      'S', 's': ScreenMode := scrmStart;
      'P', 'p': ScreenMode := scrmPreview;
      'C', 'c': ScreenMode := scrmConfig;
    end;
  end;
  if ParamCount = 0 then ScreenMode := scrmStart;

  // Create Window
  if System.HPrevInst = 0 then
  begin
    ZeroMemory(@WndClass, Sizeof(TWndClass));

    with WndClass do
    begin
      Style         := CS_VREDRAW or CS_HREDRAW or CS_SAVEBITS or CS_DBLCLKS;
      lpfnWndProc   := @WndProc;
      cbClsExtra    := 0;
      cbWndExtra    := 0;
      hbrBackground := GetStockObject(BLACK_BRUSH);
      lpszMenuName  := nil;
      lpszClassName := WndClassName;
      hInstance     := hInstance;
      hIcon         := LoadIcon(0, IDI_APPLICATION);
      hCursor       := LoadCursor(0, IDC_ARROW);
    end;
    RegisterClass(WndClass);
  end;

  if ScreenMode = scrmStart then
  begin
    GetClientRect(GetDesktopWindow, WndRect);
    AppHWND :=
      CreateWindow(
        WndClassName,
        AppName,
        WS_VISIBLE or WS_POPUP or WS_EX_TOPMOST {or WS_SYSMENU},
        WndRect.Left,
        WndRect.Top,
        WndRect.Right,
        WndRect.Bottom,
        0,
        0,
        hInstance,
        nil);
  end else
  if ScreenMode = scrmPreview then
  begin
    ParentWnd := _StrToInt(ParamStr(2));  // Get Window Handle // <---<<<
    GetClientRect(ParentWnd, WndRect);
    AppHWND :=
      CreateWindow(
        WndClassName,
        AppName,
        WS_VISIBLE or WS_POPUP,
        WndRect.Left,
        WndRect.Top,
        WndRect.Right,
        WndRect.Bottom,
        0, {ParentWnd,} // <---<<<
        0,
        hInstance,
        nil);
    SetParent(AppHWND, ParentWnd); // <---<<<
  end else // elseif ScreenMode = scrmConfig
  begin
    DialogBoxParam(hInstance, MAKEINTRESOURCE(IDD_DLG), AppHWND, @DlgProc,0);
    PostQuitMessage(0);
  end;

  UpdateWindow(AppHWND);

  // "Application.Run"
  while GetMessage(msg, 0, 0, 0) do
  begin
    TranslateMessage(msg);
    DispatchMessage(msg);
  end;

END.