On Windows platform, I want to listen to the down event of any key use RawKeyboard.instance.addListener(_handleKey), including when the input method is displayed, but the following code skips the callback function.what should I do? @dkwingsmt Thank You.

/// Process a new [RawKeyEvent] by recording the state changes and
  /// dispatching to listeners.
  bool handleRawKeyEvent(RawKeyEvent event) {
    bool shouldDispatch = true;
    if (event is RawKeyDownEvent) {
      if (event.data.shouldDispatchEvent()) {
        _keysPressed[event.physicalKey] = event.logicalKey;
      } else {
        shouldDispatch = false;
        _hiddenKeysPressed.add(event.physicalKey);
      }
    } else if (event is RawKeyUpEvent) {
      if (!_hiddenKeysPressed.contains(event.physicalKey)) {
        // Use the physical key in the key up event to find the physical key from
        // the corresponding key down event and remove it, even if the logical
        // keys don't match.
        _keysPressed.remove(event.physicalKey);
      } else {
        _hiddenKeysPressed.remove(event.physicalKey);
        shouldDispatch = false;
      }
    }
    if (!shouldDispatch) {
      return true;
    }
    // Make sure that the modifiers reflect reality, in case a modifier key was
    // pressed/released while the app didn't have focus.
    _synchronizeModifiers(event);
    assert(
      event is! RawKeyDownEvent || _keysPressed.isNotEmpty,
      'Attempted to send a key down event when no keys are in keysPressed. '
      "This state can occur if the key event being sent doesn't properly "
      'set its modifier flags. This was the event: $event and its data: '
      '${event.data}',
    );
    // Send the event to passive listeners.
    for (final ValueChanged<RawKeyEvent> listener in List<ValueChanged<RawKeyEvent>>.of(_listeners)) {
      try {
        if (_listeners.contains(listener)) {
          listener(event);
        }
      } catch (exception, stack) {
        InformationCollector? collector;
        assert(() {
          collector = () => <DiagnosticsNode>[
            DiagnosticsProperty<RawKeyEvent>('Event', event),
          ];
          return true;
        }());
        FlutterError.reportError(FlutterErrorDetails(
          exception: exception,
          stack: stack,
          library: 'services library',
          context: ErrorDescription('while processing a raw key listener'),
          informationCollector: collector,
        ));
      }
    }

    return false;
  }

@wxw-9527 This is a tricky problem, because even if we somehow hack into RawKeyboardWindows, our new keyboard system (accessible via HardwareKeyboard) also skips these events and does it at in the engine, which you can not hack into. And since other platforms use different ways to ensure keyboard events work well with IMEs, any solution that specifically targets at VK_PROCESSKEY will not be portable.
Can you tell me what you want to achieve with this?

Thank you for your reply.
I need to develop a windows program to parse the data provided by the Scanning Gun.But when starting the Chinese input method,if (!shouldDispatch) { return true; } will jump out of this method.
Now I solved my needs in other ways,It was cumbersome, but solved my problem.
http://t.csdn.cn/QDUNO

I see what you're doing here. (By the way, your current short link is broken.)

If you can hack into the engine you might want to try ImmDisableIME, which must be called before the window is created and disables IME for the entire window. Not sure if it's too strong for you.

You're great.....（给大哥跪了）
I use Focus() do what I want, but I just discovered, you have fixed it..... #104244
Now I have to think about using ImmDisableIME.
Can you help me, how to use ImmDisableIME method to disable IME? Thank you very much.

(Google Translate)

总的来说，你需要让flutter引擎在程序的窗口创建之前运行win32的ImmDisableIME函数（不需要参数）。我一时能想到有三种方案：

1. 自己修改引擎，然后找到创建窗口前的位置插这么一行就行。优点是100%理论可行，缺点是需要自己编译引擎并且以后需要自己rebase。
2. 写一个插件（flutter plugin），插件不需要开放任何接口，只需要调用这个函数。我猜测这个函数应该是在创建窗口前调用的，但不确定。优点是漂亮，甚至可以拿到pub.dev上发成库。缺点是我不确定是不是真的可行。
3. 修改应用里的runner，然后在调用flutter的任何函数前调用这个函数。优点是简单（应该可行吧……），缺点是……没有2漂亮（？）。

具体怎么做我现在在手机上看不到。如果你摸索不出来我们可以再讨论。

非常感谢您的回复！我试一试。
（题外话，你可真是个让人又爱又恨的男人。。。把路堵的死死的。）

I found the documentation for the ImmDisableIME function, but I didn't find the right place to call this function, because it requires parameters I didn't find in any file under the windows/runner path.

A lot of websites mentioned that the parameter should simply be -1 to disable all threads in this process.

ImmDisableIME(-1);

https://github.com/MicrosoftDocs/sdk-api/blob/docs/sdk-api-src/content/immdev/nf-immdev-immdisableime.md

https://cpp.hotexamples.com/examples/-/-/ImmDisableIME/cpp-immdisableime-function-examples.html

https://www.tokovalue.jp/function/ImmDisableIME.htm

I'm very sorry to trouble you again.
Because I don't know anything about Windows native development. I tried many times, Including asking questions on stackoverflow, But after adding ImmDisableIME(-1);, it will report an error when compiling.

What's the compiling error?

use ImmDisableIME(-1);:
mian.cpp
win32_window.cpp

Exception when using DWORD dwParam = (DWORD)(-1); ImmDisableIME(dwParam);:
win32_window.obj : error LNK2019: �޷��������ⲿ���� ImmDisableIME������ "public: bool __cdecl Win32Window::CreateAndShow(class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > const &,struct Win32Window::Point const &,struct Win32Window::Size const &)" (?CreateAndShow@Win32Window@@QEAA_NAEBV?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@AEBUPoint@1@AEBUSize@1@@Z) �������˸÷��� [W:\WorkSpace\RouXinPai\workpad\build\windows\runner\workpad.vcxproj] W:\WorkSpace\RouXinPai\workpad\build\windows\runner\Debug\workpad.exe : fatal error LNK1120: 1 ���޷��������ⲿ���� [W:\WorkSpace\RouXinPai\workpad\build\windows\runner\workpad.vcxproj] Exception: Build process failed.

I think it's because you didn't provide the correct lib file to link ImmDisableIME. Maybe try adding

#pragma comment(lib, "imm32.lib")

https://blog.csdn.net/sleep_0/article/details/50452483

Thanks for your help.
After adding #pragma comment(lib, "imm32.lib") to the file header of win32_window.cpp, add ImmDisableIME(GetCurrentThreadId()) in CreateAndShow method, can disable the IME.
Thanks again.

Awesome! Glad to know.