private static Theme ChangeTheme(ResourceDictionary resources, Theme oldTheme, Theme newTheme)
{
var themeChanged = false;
if (oldTheme != newTheme)
{
resources.BeginInit();
ResourceDictionary oldThemeResource = null;
if (oldTheme.IsNotNull())
{
oldThemeResource = resources.MergedDictionaries.FirstOrDefault(d => AreResourceDictionarySourcesEqual(d, oldTheme.Resources));
}
resources.MergedDictionaries.Add(newTheme.Resources);
if (oldThemeResource.IsNotNull())
{
resources.MergedDictionaries.Remove(oldThemeResource);
}
themeChanged = true;
resources.EndInit();
}
if (themeChanged)
{
OnThemeChanged(newTheme);
}
return(newTheme);
}