BrightSharp.Toolkit/docs/help/apply-themes.md

Apply themes with App.xaml

App.xaml

<ResourceDictionary>
    <ResourceDictionary.MergedDictionaries>
        
        <ResourceDictionary Source="/brightsharp;component/themes/style.classic.xaml" />
        <ResourceDictionary Source="/brightsharp;component/themes/theme.xaml" />
        
    </ResourceDictionary.MergedDictionaries>

</ResourceDictionary>

Change themes by ThemeManager

Change by ThemeManager

    ThemeManager.CurrentTheme = ColorThemes.DarkBlue;

Change themes by ResourceDictionary

As default we use Classic theme. You also can change theme by adding resource dictionary after generic.xaml. Use one of them:

<ResourceDictionary Source="/brightsharp;component/themes/style.classic.xaml" />
<ResourceDictionary Source="/brightsharp;component/themes/style.devlab.xaml" />
<ResourceDictionary Source="/brightsharp;component/themes/style.silver.xaml" />
<ResourceDictionary Source="/brightsharp;component/themes/style.blue.xaml" />
<ResourceDictionary Source="/brightsharp;component/themes/style.darkblue.xaml" />

NOTES

You can use custom window style named BrightSharpWindowStyle. Also defined additional useful styles and extensions. For more info see Demo source code.