Get the text of an edit control as it changes?

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C++

Win32

I'm hanging on to my edit control window handle and calling GetWindowText every time I get a WM_COMMAND with EN_CHANGE on the parent window

From there I don't get any reasonable value back. It's just an empty string.

How the heck do I get the text from an edit control if not with GetWindowText?

Why doesn't the code in what I tried work?

What I have tried:

static LRESULT CALLBACK WindowProcGpio(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    if(uMsg==WM_CREATE) {
        gpio_t& g = *(gpio_t*)((LPCREATESTRUCT) lParam)->lpCreateParams;
        SetWindowLongPtrW(hWnd,GWLP_USERDATA,(LONG_PTR)&g);
        HWND hwnd_st_u, hwnd_ed_u;
        int x, w, y, h;
        y = 10; h = 20;
        x = 10; w = 50;
        hwnd_st_u = CreateWindowW(L"static", L"ST_U",
                              WS_CHILD | WS_VISIBLE | WS_TABSTOP,
                              x, y, w, h,
                              hWnd, (HMENU)(501),
                              (HINSTANCE) GetModuleHandle(NULL), NULL);
        SetWindowTextW(hwnd_st_u, L"Value:");

        x += w; w = 60;
        hwnd_ed_u = CreateWindowW(L"edit", L"",
                                    WS_CHILD | WS_VISIBLE | WS_TABSTOP | (WS_DISABLED*(!g.is_input()))
                                    | ES_LEFT | WS_BORDER,
                                    x, y, w, h,
                                    hWnd, (HMENU)(502),
                                    (HINSTANCE) GetModuleHandle(NULL), NULL);
        wchar_t val[64];
        if(g.value==HIGH) {
            wcscpy(val,L"HIGH");
        } else if(g.value==LOW) {
            wcscpy(val,L"LOW");
        } else {
            _itow(g.value,val,10);
        }
        SetWindowTextW(hwnd_ed_u, val);
        g.hwnd_text = hwnd_ed_u;
        
    }
    if(uMsg==WM_COMMAND) {
        if(HIWORD (wParam) == EN_CHANGE) {
            uint8_t gpio = GetWindowLongPtrW(hWnd,GWLP_USERDATA);
            wchar_t sz[1024];
            gpio_t& g = gpios[gpio];
            GetWindowTextW(g.hwnd_text,sz,sizeof(sz)/sizeof(wchar_t));
            char ssz[1024];
            GetWindowTextA(g.hwnd_text,ssz,sizeof(ssz));
            Serial.print(ssz);
            Serial.print("\r\n");
            sz[63]=0;
            if(0==wcsicmp(sz,L"LOW")) {
                g.value=LOW;
            } else if(0==wcsicmp(sz,L"HIGH")) {
                g.value=HIGH;
            } else {
                size_t l = wcslen(sz);
                bool isnum = true;
                for(int i = 0;i<l;++i) {
                    if(!iswdigit(sz[i])) {
                        isnum = false;
                        break;
                    }
                }
                if(isnum) {
                    g.value = _wtoi(sz);
                }
            }
        }
        return 0;
    }
    if (uMsg == WM_CLOSE) {
        gpio_t& g = *(gpio_t*)GetWindowLongPtrW(hWnd,GWLP_USERDATA);
        g.hwnd_text = NULL;
    }
   
    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}