[NumLock]

Код:

program CreateWindowAPI;

uses
  Windows, Messages;

var
  AWndClass: WNDCLASS;
  AWnd: HWND;
  AMsg: TMsg;

function WindowProc(AWnd: HWND; Msg: Integer;
  wParam: WPARAM; lParam: LPARAM): Longint; stdcall;
begin
  case Msg of
    WM_CLOSE: begin
      PostQuitMessage(0);
      Result:=0;
    end;
    else Result:=DefWindowProc(AWnd, Msg, wParam, lParam);
  end
end;

begin
  AWndClass.Style:=CS_HREDRAW or CS_VREDRAW;
  AWndClass.lpfnWndProc:=@WindowProc;
  AWndClass.cbClsExtra:=0;
  AWndClass.cbWndExtra:=0;
  AWndClass.hInstance:=HInstance;
  AWndClass.hIcon:=0;
  AWndClass.hCursor:=LoadCursor(0, IDC_ARROW);
  AWndClass.hbrBackground:=HBRUSH(COLOR_WINDOW);
  AWndClass.lpszMenuName:=nil;
  AWndClass.lpszClassName:='TWINAPIFORM';
  RegisterClass(AWndClass);
  AWnd:=CreateWindowEx(0, AWndClass.lpszClassName, AWndClass.lpszClassName,
    WS_OVERLAPPEDWINDOW,
    Integer(CW_USEDEFAULT), Integer(CW_USEDEFAULT),
    320, 240,
    0, 0, HInstance, nil);
  ShowWindow(AWnd, SW_SHOWNORMAL);
  UpdateWindow(AWnd);
  while GetMessage(AMsg, 0, 0, 0) do
  begin
    TranslateMessage(AMsg);
    DispatchMessage(AMsg);
  end;
  DestroyWindow(AWnd);
  UnregisterClass(AWndClass.lpszClassName, HInstance);
  AWnd:=FindWindow(AWndClass.lpszClassName, AWndClass.lpszClassName);
  if AWnd<>0 then SendMessage(AWnd, WM_CLOSE, 0, 0);
end.