Public API Requirements : ThemeManager, ThemeMode ??

[singhashish-wpf]

Description

There are a few public API changes related to theme management for Fluent theme that may be needed in the future, but we are not set on what those APIs should be to make it feature complete.

Currently we have experimental ThemeMode APIs for Application and Window which are only Fluent specific and do not function for other themes. This needs to be changed and we need to find a better way to deal with theme and theme variants.

Previously there has been a lot of discussion on this topic on the following threads :

• [API Proposal]: Win 11 Theming - Theme Manager [Draft] #8759
• [API Proposal]: FluentWindows Theme Switch in WPF #8932

WPF.UI has the following APIs :

• ThemeService
• ApplicationThemeManager
• SystemThemeManager
• SystemThemeWatcher
• ApplicationTheme
• SystemTheme
• ThemeChangedEvent
• IThemeService

WPF may need some or most of these APIs, but that can be discussed only after we finalize the approach on how we are going to use Fluent as default theme.