Program.cs

// Fluent API example demonstrating IRunnable with automatic disposal and result extraction

using Terminal.Gui.App;
using Terminal.Gui.Drawing;
using Terminal.Gui.Resources;
using Terminal.Gui.ViewBase;
using Terminal.Gui.Views;

var smokeTest = args.Length > 0 && args [0] == "--smoke-test";

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

if (smokeTest)
{
    using CancellationTokenSource cts = new (TimeSpan.FromSeconds (2));
    await app.RunAsync<ColorPickerView> (cts.Token);
    Console.WriteLine ("Smoke test passed.");
    app.Dispose ();

    return;
}

app.Run<ColorPickerView> ();

// Run the application with fluent API - automatically creates, runs, and disposes the runnable
Color? result = app.GetResult () as Color?;

// Shut down the app with Dispose before we can use Console.WriteLine
app.Dispose ();

if (result is not null)
{
    Console.WriteLine (@$"Selected Color: {result}");
}
else
{
    Console.WriteLine (@"No color selected");
}

/// <summary>
///     A runnable view that allows the user to select a color.
///     Demonstrates the Runnable with type pattern with automatic disposal.
/// </summary>
public class ColorPickerView : Runnable<Color?>
{
    public ColorPickerView ()
    {
        Title = "Select a Color (Esc to quit)";
        BorderStyle = LineStyle.Single;
        Height = Dim.Auto ();
        Width = Dim.Auto ();

        // Add instructions
        Label instructions = new ()
        {
            Text = "Use arrow keys to select a color, Enter to accept",
            X = Pos.Center (),
            Y = 0
        };

        // Create color picker
        ColorPicker colorPicker = new ()
        {
            X = Pos.Center (),
            Y = Pos.Bottom (instructions),
            Style = new ColorPickerStyle
            {
                ShowColorName = true,
                ShowTextFields = true
            }
        };
        colorPicker.ApplyStyleChanges ();

        // Create OK button
        Button okButton = new ()
        {
            Title = "_OK",
            X = Pos.Align (Alignment.Center),
            Y = Pos.AnchorEnd (),
            IsDefault = true
        };

        okButton.Accepting += (s, e) =>
        {
            // Extract result before stopping
            Result = colorPicker.Value;
            RequestStop ();
            e.Handled = true;
        };

        // Create Cancel button
        Button cancelButton = new ()
        {
            Title = Strings.btnCancel,
            X = Pos.Align (Alignment.Center),
            Y = Pos.AnchorEnd ()
        };

        cancelButton.Accepting += (s, e) =>
        {
            // Don't set result - leave as null
            RequestStop ();
            e.Handled = true;
        };

        // Add views
        Add (instructions, colorPicker, okButton, cancelButton);
    }

    protected override bool OnIsRunningChanging (bool oldIsRunning, bool newIsRunning)
    {
        // Alternative place to extract result before stopping
        // This is called before the view is removed from the stack
        if (!newIsRunning && Result is null)
        {
            // User pressed Esc - could extract current selection here
            //Result = SelectedColor;
        }

        return base.OnIsRunningChanging (oldIsRunning, newIsRunning);
    }
}