Workaround visual bug with Windows Phone when you change themes, and then fast app switch back

gistfile1.cs

void WorkaroundThemeResumeBugInWindowsPhone()
{
    var backgroundColor = (Color)Application.Resources["PhoneBackgroundColor"];
    var chromeColor = (Color)Application.Resources["PhoneChromeColor"];
    var foregroundColor = (Color)Application.Resources["PhoneForegroundColor"];
    RootFrame.Navigated += (sender, args) =>
    {
        SystemTray.BackgroundColor = backgroundColor;
        SystemTray.ForegroundColor = foregroundColor;

        var page = args.Content as Page;
        if (page == null) return;

        var bindableAppBar = page.FindChildOfType<BindableAppBar>();
        if (bindableAppBar != null)
        {
            bindableAppBar.BackgroundColor = chromeColor;
            bindableAppBar.ForegroundColor = foregroundColor;
        }

        var appBar = page.FindChildOfType<ApplicationBar>();
        if (appBar != null)
        {
            appBar.BackgroundColor = chromeColor;
            appBar.ForegroundColor = foregroundColor;
        }
    };
}