[Preview 4] HighContrastChanged crashes app

[asklar]

Found while upgrading react native windows to consume WinUI 3 Preview 4
We call Windows.UI.ViewManagement.AccessibilitySettings.HighContrastChanged. This API worked in Preview 3 in both UWP and Desktop, but in Preview 4 this API crashes in Desktop apps.
This worked in previous previews because XAML was calling an unsupported API (to create an invisible CoreWindow) and as a side effect some system APIs like this one worked

Could we update the relnotes @anawishnoff @ryandemopoulos regarding the HighContrastChanged event and other APIs/Events that won't work? I see there is a partial list in the notes already but this one seems like it fell through the cracks.
https://docs.microsoft.com/en-us/windows/apps/winui/winui3/#known-issues
Are there others that might be missing from the relnotes?

[anawishnoff]

Thanks! I've made a request to update the release notes, and will continue to keep an eye out for other APIs that may have become unsupported.

@JesseCol for FYI.

[citelao]

@JesseCol @asklar, what's the workaround here? How can apps detect if high contrast is enabled? As far as I can tell, we'd have to listen to WM_SETTINGCHANGE and read SPI manually, I think.

[JesseCol]

Hi, does this ThemeSettings.Changed API work for you?

https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.system.themesettings.changed?view=windows-app-sdk-1.4

[adstep]

This still repros for me on 1.5.240802000. Just subscribing to the HighContrastChanged event causes a crash for me.

[JesseCol]

Hi, did you try the ThemeSettings.Changed event instead? https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.system.themesettings.changed?view=windows-app-sdk-1.4

[adstep]

Got it working with ThemeSettings.