procedure TForm1.Button1Click(Sender: TObject);
Var
wh, mh : THandle;
id : Word;
begin
wh := findwindow(nil, '计算器');
if wh<> 0 then
begin
mh := GetMenu(wh);
mh := GetSubMenu(mh, 2); //取得帮助菜单句柄
id := GetMenuitemID(mh, 2); //取得关于菜单的ID
PostMessage(wh, WM_COMMAND, MAKEWPARAM(id, 0), 0);
end;
end;