private bool NewMethod() { tester = !tester; if (tester) { ThemeManager.SetCustomTheme(new System.Uri("/UnderDev;component/CustomThemeResources.xaml", System.UriKind.Relative), Theme.Light); ThemeManager.ToLightTheme(); } else { ThemeManager.SetCustomTheme(new System.Uri("/UnderDev;component/LightThemeResources.xaml", System.UriKind.Relative), Theme.Light); ThemeManager.ToLightTheme(); } B1.RaiseCanExecuteChanged(); B2.RaiseCanExecuteChanged(); return(tester); }