String->to->L"str"

int Key = -1;
    if (Key != Application->MessageBox(L"Text", L"Caption",
        MB_YESNO | MB_ICONQUESTION | MB_DEFBUTTON2)) {
        Application->MessageBox(IntToStr(Key).c_str(), L"Caption",
            MB_ICONQUESTION | MB_DEFBUTTON2);
    }