title: Win32 Detect if my window is running in Dark Mode on Windows 10+
body: <p>I would like my Win32 application to be able to detect if a window is actually running in Dark Mode. I know about <a href="https://stackoverflow.com/questions/51334674/how-to-detect-windows-10-light-dark-mode-in-win32-application">this answer</a>, which suggests reading a registry key for the user setting. That's fine, and it works for me. But many applications do not honor that setting.</p>
  <p>I would like to find out which appearance my actual window has. My program is a 3rd-party plugin that runs inside an application I do not control. Currently that host application does not support Dark Mode on Windows, but a new version could potentially start supporting it. I would like to allow my program to detect if it does. I would also like to continue to support older versions of the app, without having to resort to a manual list of versions that do or don't support Dark Mode.</p>
  <p>For readers that know something about macOS APIs, I am hoping to find something similar to the <code>effectiveAppearance</code> property on macOS views.</p>