Code that extends the window content into the title bar

appContentInTitleBar.cs

//Inside OnLaunched method in App.Xaml.cs

var appView = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView();
 
 if (Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Winodows.UI.ViewManagemnt.ApplicationViewTitleBar))
            {
                ApplicationViewTitleBar formattableTitleBar = appView.TitleBar;
                formattableTitleBar.ButtonBackgroundColor = Colors.Transparent;
                CoreApplicationViewTitleBar coreTitleBar = CoreApplication.GetCurrentView().TitleBar;
                coreTitleBar.ExtendViewIntoTitleBar = true;
                appView.SetDesiredBoundsMode(ApplicationViewBoundsMode.UseCoreWindow);
            }