SDL + win32 control event not working?

SDL Development
1

Hello,

I have an application using SDL2/opengl (let’s try to forget opengl for a moment). I am trying to add scintilla as a text editor. But I have issues with getting events related to the created scintilla control. Relevant code:

(initialization)

HMODULE hmod = LoadLibrary(L"Scintilla.DLL");

hwndScintilla = CreateWindowEx(0,
L"Scintilla", L"", WS_CHILD | WS_VISIBLE | WS_CLIPCHILDREN,
10, 10, 500, 400, hwndMain, GetFreeControlID(), GetModuleHandle(NULL), NULL);

(main - before SDL event loop)
SDL_EventState(SDL_SYSWMEVENT, SDL_ENABLE);

(main - SDL event loop)

while (SDL_PollEvent(&ev)) {
    if (ev.type == SDL_SYSWMEVENT) {
        XEEDITOR::ProcessSysEvents(ev);
    }
(...)

(actual event processing)

void ProcessSysEvents(SDL_Event& ev) {
    SDL_SysWMmsg* msg = ev.syswm.msg;
    if (msg->msg.win.msg == WM_NOTIFY) {
        NMHDR* lpnmhdr = (LPNMHDR)msg->msg.win.lParam;
        if (lpnmhdr->hwndFrom == hwndScintilla) {
            switch (lpnmhdr->code) {
                case SCN_CHARADDED:
                    PLOGD << "Character added";
                    break;
            }
        }
    }
}

Apparently, lpnmhdr->hwndFrom never becomes equal to hwndScintilla.
Any ideas?