ModalWindow change title

[Guiaki]

I was wondering if there was something like that possible, ex:

local newModalWindow = modalWindow:getId()
newModalWindow:changeTitle("New title")

Can I change the title of the current ModalWindow? (Or open a new one without user noticing)

--EDIT--

Just made the function myself:

int32_t LuaScriptInterface::luaModalWindowChangeTitle(lua_State* L)
{
    // modalWindow:changeTitle(text)
    const std::string& text = getString(L, 2);
    ModalWindow* window = getUserdata<ModalWindow>(L, 1);
    if (window) {
        window->title = text;
        pushBoolean(L, true);
    }
    else {
        pushNil(L);
    }
    return 1;
}

Do I need to put the declaration of luaModalWindowChangeTitle anywhere else before compiling? ( I already put on luascript.h and luascript.cpp)