Program.cs

// This is a test application for a self-contained single file.

using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using Terminal.Gui.App;
using Terminal.Gui.Configuration;
using Terminal.Gui.Drawing;
using Terminal.Gui.Input;
using Terminal.Gui.ViewBase;
using Terminal.Gui.Views;

namespace SelfContained;

public static class Program
{
    private static async Task Main (string[] args)
    {
        var smokeTest = args.Length > 0 && args [0] == "--smoke-test";

        if (smokeTest)
        {
            ConfigurationManager.Enable (ConfigLocations.All);
            Application.AppModel = AppModel.Inline;
            IApplication app = Application.Create ();
            app.Init ();

            using CancellationTokenSource cts = new (TimeSpan.FromSeconds (2));
            using ExampleWindow smokeWindow = new ();
            await app.RunAsync (smokeWindow, cts.Token);
            Console.WriteLine ("Smoke test passed.");
            app.Dispose ();

            return;
        }

#pragma warning disable IL2026 // Run() has attributes for AOT compatibility
        Run ();
#pragma warning restore IL2026
    }

    [RequiresUnreferencedCode ("Calls Terminal.Gui.Application.Run<T>(Func<Exception, Boolean>, IDriver)")]
    private static void Run ()
    {
        ConfigurationManager.Enable (ConfigLocations.All);

        // Use Inline mode — renders below the shell prompt without alternate screen buffer
        Application.AppModel = AppModel.Inline;

        IApplication app = Application.Create ();
        app.Init ();

        #region The code in this region is not intended for use in a self-contained single-file. It's just here to make sure there is no functionality break with localization in Terminal.Gui using single-file

        if (Equals (Thread.CurrentThread.CurrentUICulture, CultureInfo.InvariantCulture) &&
            Application.SupportedCultures?.Count == 0)
        {
            // Only happens if the project has <InvariantGlobalization>true</InvariantGlobalization>
            Debug.Assert (Application.SupportedCultures.Count == 0);
        }
        else
        {
            Debug.Assert (Application.SupportedCultures?.Count > 0);
            Debug.Assert (Equals (CultureInfo.CurrentCulture, Thread.CurrentThread.CurrentUICulture));
        }

        #endregion

        using ExampleWindow exampleWindow = new ();
        var userName = app.Run (exampleWindow) as string;

        // Shutdown the application in order to free resources and clean up the terminal
        app.Dispose ();

        // To see this output on the screen it must be done after shutdown,
        // which restores the previous screen.
        Console.WriteLine ($@"Username: {userName}");
    }
}

// Defines a top-level window with border and title
public class ExampleWindow : Runnable<string>
{
    public ExampleWindow ()
    {
        BorderStyle = LineStyle.Single;
        Title = $"Example App ({Application.GetDefaultKey (Command.Quit)} to quit)";

        // Create input components and labels
        Label usernameLabel = new () { Text = "Username:" };

        TextField userNameText = new ()
        {
            // Position text field adjacent to the label
            X = Pos.Right (usernameLabel) + 1,

            // Fill remaining horizontal space
            Width = Dim.Fill ()
        };

        Label passwordLabel = new ()
            { Text = "Password:", X = Pos.Left (usernameLabel), Y = Pos.Bottom (usernameLabel) + 1 };

        TextField passwordText = new ()
        {
            Secret = true,

            // align with the text box above
            X = Pos.Left (userNameText),
            Y = Pos.Top (passwordLabel),
            Width = Dim.Fill ()
        };

        // Create login button
        Button btnLogin = new ()
        {
            Text = "Login",
            Y = Pos.Bottom (passwordLabel) + 1,

            // center the login button horizontally
            X = Pos.Center (),
            IsDefault = true
        };

        // When login button is clicked display a message popup
        btnLogin.Accepted += (_, _) =>
        {
            if (userNameText.Text == "admin" && passwordText.Text == "password")
            {
                MessageBox.Query (App!, "Logging In", "Login Successful", "Ok");
                Result = userNameText.Text;
                App?.RequestStop ();
            }
            else
            {
                MessageBox.ErrorQuery (App!, "Logging In", "Incorrect username or password", "Ok");
            }
        };

        // Add the views to the Window
        Add (usernameLabel, userNameText, passwordLabel, passwordText, btnLogin);
    }
}