CreateWindowEx, Parent + Child erzeugen

[turboPASCAL]

Mach es so:

Delphi-Quellcode:

Procedure CreateWindows;
var
  wa, wb, wc, wd: TWndClass;
  hWindowParent, hWindowChild : Thandle;
  hMyChild : THandle;
begin

  if FindWindow('MyParent','') = 0 then
    begin
      zeromemory(@wa, sizeof(wa));  // <--<<
      with wa do begin
        lpszClassName := 'MyParent';
        lpfnWndProc   := @MainWndProc;
        Style         := CS_VREDRAW or CS_HREDRAW;
        hInstance     := hInstance;
        hIcon         := LoadIcon(0, IDI_APPLICATION);
        hCursor       := LoadCursor(0, IDC_ARROW);
        hbrBackground := (COLOR_WINDOW + 1);
        lpszMenuName  := nil;
        cbClsExtra    := 0;
        cbWndExtra    := 0;
      end;

      zeromemory(@wb, sizeof(wb)); // <--<<
      with wb do begin
        lpszClassName := 'MyChild';
        lpfnWndProc   := @ChildWndProc;
        Style         := CS_VREDRAW or CS_HREDRAW;
        hInstance     := hMyChild;
        hIcon         := LoadIcon(0, IDI_APPLICATION);
        hCursor       := LoadCursor(0, IDC_ARROW);
        hbrBackground := (COLOR_BTNFACE + 1);  // <--<<
        lpszMenuName  := nil;
        cbClsExtra    := 0;
        cbWndExtra    := 0;
      end;

      if Windows.RegisterClass(wa) = 0 then // <--<<
        MessageBox(0, 'Kann Fensterklasse nicht registrieren.', 'MyParent', MB_OK);

      if Windows.RegisterClass(wb) = 0 then // <--<<
        MessageBox(0, 'Kann Fensterklasse nicht registrieren.', 'MyChild', MB_OK);

      //create main hwnd:
      hWindowParent := CreateWindowEx(WS_EX_TOPMOST Or WS_EX_TOOLWINDOW,
       'MyParent',
        '',
        WS_POPUP or windows.ws_visible, // <--<<
        CW_USEDEFAULT, 0,
        100, 100, // <--<<
        0,
        0,
        hInstance,
        nil);

    if hWindowParent <> 0 then // <--<<
      hWindowChild := CreateWindowEx(0, // <--<<
        'MyChild',
        nil,
        WS_CHILD or ws_visible, // <--<<
        CW_USEDEFAULT, 0,
        40, 40, // <--<<
        hWindowParent,
        0,
        hMyChild,
      nil);

  end;
end;

das funkltioniert mit sicherheit.