Streaming TextChanged event as IAsyncEnumerable

WinFormsAsyncEnumerable.cs

// verifying https://twitter.com/noseratio/status/1490181545746841602?s=20&t=9FIQA5E2Qz9oHLSEQIW7Ew

namespace textbox;

using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Threading.Channels;

static class Program
{
    [STAThread]
    static void Main()
    {
        ApplicationConfiguration.Initialize();
        Application.Run(new MainForms());
    }    
}

public class TextBox: System.Windows.Forms.TextBox
{
    public async IAsyncEnumerable<EventArgs> OnChanged(
        [EnumeratorCancellation]
        CancellationToken cancellationToken)
    {
        var channel = Channel.CreateUnbounded<EventArgs>();

        void onTextChanged(object? _, EventArgs e) =>
            channel.Writer.TryWrite(e);

        this.TextChanged += onTextChanged;
        try
        {
            await foreach (var ev in channel.Reader.ReadAllAsync(cancellationToken))
            {
                yield return ev;
            }
        }
        finally
        {
            this.TextChanged -= onTextChanged;
            channel.Writer.Complete();
        }
    }
}

public partial class MainForms : Form
{
    public MainForms()
    {
        InitializeComponent();
        var textBox = new TextBox() { Visible = true, Dock = DockStyle.Fill };
        this.Controls.Add(textBox);
        
        async Task OnChanged()
        {
            await foreach (var onChanged in textBox!.OnChanged(CancellationToken.None))
            {
                Trace.WriteLine("OnChanged");
            }
        }

        _ = Task.Run(() => OnChanged());
    }
}