Shows how to use Rx to capture keypress events. I use it for fastforward and reverse in the media sense. ABetterKeyPressCapture.cs was written by Chris Harris @cwharris. I appreciate his answer on StackOverflow.

ABetterKeyPressCapture.cs

using System;
using System.Collections.Generic;
using System.Reactive;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Windows.Forms;
namespace RxStuff
{
class Program
    {
        private const int KeyPressThresholdMilliSec = 200;
        static void Main(string[] args)
        {
            //var txt = new TextBox();

            var frm = new System.Windows.Forms.Form()
            {
                //Controls = { txt }
            };

            var disposables = new List<IDisposable>();

            var t = TimeSpan.FromMilliseconds(KeyPressThresholdMilliSec);
            //Hook up fast forward
            var upRightArrow = Observable.FromEventPattern<KeyEventArgs>(frm, "KeyUp")
                .Where(x => x.EventArgs.KeyCode == Keys.Right);

            upRightArrow.Subscribe(x =>
            {
                Console.WriteLine("FastForward STOP");
            });

            var downRightArrow = Observable.FromEventPattern<KeyEventArgs>(frm, "KeyDown")
                .Where(x => x.EventArgs.KeyCode == Keys.Right)
                .Take(1)
                .Concat(upRightArrow.Take(1).IgnoreElements())
                .Repeat();

            //hook up frame increment
            var tapFastForward = downRightArrow.SelectMany(x =>
                Observable.Amb(
                    Observable.Empty<EventPattern<KeyEventArgs>>().Delay(t),
                    upRightArrow.Take(1)
                ))
                .Publish()
                .RefCount();

            tapFastForward.Subscribe(x =>
            {
                Console.WriteLine("Increment Frame");
            });

            var longPressFastForward = downRightArrow.SelectMany(x =>
                Observable.Return(x).Delay(t).TakeUntil(tapFastForward)
                ).Subscribe(x =>
                {
                    Console.WriteLine("FastForward GO");
                });

            using (new CompositeDisposable(disposables))
            {
                Application.Run(frm);
            }
        }
    }
}

GeneralizedKeyPressExt.cs

public static class KeyPressExtensions
{
    public static void WireKey(this object target, Key key, Action tapAction, Action longPressAction, Action keyUpAction)
    {
        const int tapTimeMilliSec = 300;
        var t = TimeSpan.FromMilliseconds(tapTimeMilliSec);

        var keyUp = Observable.FromEventPattern<KeyEventArgs>(target, "KeyUp")
            .Where(x => x.EventArgs.Key == key);
        keyUp.Subscribe(a => keyUpAction());

        var keyDown = Observable.FromEventPattern<KeyEventArgs>(target, "KeyDown")
            .Where(x => x.EventArgs.Key == key)
            .Take(1)
            .Concat(keyUp.Take(1).IgnoreElements())
            .Repeat();

        var tapKey = keyDown.SelectMany(x =>
            Observable.Amb(
                Observable.Empty<EventPattern<KeyEventArgs>>().Delay(t),
                keyUp.Take(1)
            ))
            .Publish()
            .RefCount();

        tapKey.Subscribe(a => tapAction());

        var longPress = keyDown.SelectMany(x => Observable.Return(x).Delay(t).TakeUntil(tapKey))
            .Subscribe(a => longPressAction());

    }
}

KeyPressCapture.cs

using System;
using System.Collections.Generic;
using System.Reactive;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Windows.Forms;
namespace RxStuff
{
class Program
    {
        private const int KeyPressThresholdMilliSec = 200;
        static void Main(string[] args)
        {
            //var txt = new TextBox();

            var frm = new System.Windows.Forms.Form()
            {
                //Controls = { txt }
            };

            var disposables = new List<IDisposable>();

            //start FF when we get 2 key presses within the threshold time
            disposables.Add(Observable.FromEventPattern<KeyEventArgs>(frm, "KeyDown")
                .Where(k => k.EventArgs.KeyCode == Keys.Right)
                .Timestamp()
                .Buffer(2)
                .Where(x => (x[1].Timestamp - x[0].Timestamp).Milliseconds < KeyPressThresholdMilliSec)
                .Subscribe(x => Console.WriteLine("FastForward GO")));

            //stop ff on the key up
            disposables.Add(Observable.FromEventPattern<KeyEventArgs>(frm, "KeyUp")
                .Where(k => k.EventArgs.KeyCode == Keys.Right)
                .Subscribe(x => { Console.WriteLine("FastForward STOP"); }));


            disposables.Add(Observable.FromEventPattern<KeyEventArgs>(frm, "KeyDown")
                .Where(k => k.EventArgs.KeyCode == Keys.Left)
                .Timestamp()
                .Buffer(2)
                .Where(x => (x[1].Timestamp - x[0].Timestamp).Milliseconds < KeyPressThresholdMilliSec)
                .Subscribe(x => Console.WriteLine("Reverse GO")));

            disposables.Add(Observable.FromEventPattern<KeyEventArgs>(frm, "KeyUp")
                .Where(k => k.EventArgs.KeyCode == Keys.Left)
                .Subscribe(x => { Console.WriteLine("Reverse STOP"); }));

            using (new CompositeDisposable(disposables))
            {
                Application.Run(frm);
            }
        }
    }
}