Proposal: Support theming of user32 controls like the system menu

[shaheedmalik]

I noticed this months ago but I didn't know where to put it at the time. So, I kinda forgot about it.

This reddit post reminded me of it.
https://www.reddit.com/r/Windows10/comments/hhwn2z/so_when_i_can_expect_the_context_menus_to_have/

If you right click on the title bar in a Win32 and UWP app, the context menu doesn't match the styling of the context menu used in the app. It also does not match the system selected theme.

I have Dark Mode selected.
Win32:

UWP:

[mdtauk]

This should produce a theme aware Xaml Context Menu with WinUI 3 apps - there is no backwards compatible reasons not to

[stevewri]

The system menu is a user32 control dating from before the advent of theming. It's possible that "lifting" some of this code would allow us to update it to support theming. That's more than a bugfix, so let me update the title to a proposal that we can consider in the context of Reunion.

[sylveon]

Related to #41. Using the APIs I named there gives you a dark context menu, like currently seen on Explorer:

[XamDR]

Related to #41. Using the APIs I named there gives you a dark context menu, like currently seen on Explorer:

Hi. Would you like to share a basic demo code to get a dark context menu? I've seen the other issue, and there are different (undocumented) methods there that I don't know exactly what would be used to accomplish such task.

[sylveon]

See https://github.com/ysc3839/win32-darkmode. There's a bit more setup involved if your app shows more than a context menu, but if it only shows context menus (eg a tray icon only app), only calling SetPreferredAppMode and AllowDarkModeForWindow for the window that hosts the context menus is sufficient.

[sylveon]

[AzAgarampur]

This can be related to #41 where the undocumented dark theme api from uxtheme.dll is being used to enable dark styling on common controls, the ribbon framework, and more.

Also, it'd be great in general if menu bars could be could listen to dark mode, not just the context menus themselves.

[kaetemi]

That white menu bar as seen in the last screenshot is horrible too. Doesn't even follow the configured system palette at all (it's supposed to be some grayish color.) Just appears to be hardcoded to be white everywhere currently, for some reason... It does make every classic application look pretty ugly.