用例

我想用Flutter构建一个virtual keyboard。我的灵感来自windows虚拟键盘“osk”（只需在cmd中运行“osk”）。每当我在不同的窗口中键入内容时，我都不（！）想失去焦点。

问题

flutter-app（桌面，windows）总是抢着焦点，我假设它是在main.cpp中配置的，但我还没有找到如何达到和osk一样的效果。
如何严格禁止窗口获得任何焦点？
下面是main.cpp代码：

#include <flutter/dart_project.h>
#include <flutter/flutter_view_controller.h>
#include <windows.h>

#include "flutter_window.h"
#include "utils.h"

int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
                      _In_ wchar_t *command_line, _In_ int show_command)
{
  // Attach to console when present (e.g., 'flutter run') or create a
  // new console when running with a debugger.
  if (!::AttachConsole(ATTACH_PARENT_PROCESS) && ::IsDebuggerPresent())
  {
    CreateAndAttachConsole();
  }

  // Initialize COM, so that it is available for use in the library and/or
  // plugins.
  ::CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);

  flutter::DartProject project(L"data");

  std::vector<std::string> command_line_arguments =
      GetCommandLineArguments();

  project.set_dart_entrypoint_arguments(std::move(command_line_arguments));

  FlutterWindow window(project);
  Win32Window::Point origin(0, 0);
  Win32Window::Size size(1024, 768);
  if (!window.CreateAndShow(L"windows", origin, size))
  {
    return EXIT_FAILURE;
  }
  window.SetQuitOnClose(true);

  ::MSG msg;
  while (::GetMessage(&msg, nullptr, 0, 0))
  {
    ::TranslateMessage(&msg);
    ::DispatchMessage(&msg);
  }

  ::CoUninitialize();
  return EXIT_SUCCESS;
}