C#

using System;
using System.Windows.Forms;

namespace vdp
{
    public partial class FormMain : Form
    {
        private Poker poker;
        // using a local field but could be global
        private int credits;

        public FormMain()
        {
            InitializeComponent();
            poker = new Poker();
            labelWinnings.Text = "0";
            poker.UpdateWinnings += new EventHandler<WinningsEventArgs>(poker_UpdateWinnings);
            DoubleClick += new EventHandler(FormMain_DoubleClick);
        }

        void FormMain_DoubleClick(object sender, EventArgs e)
        {
            /* Every time form is double clicked game is played.
             * At the end of the game UpdateWinnings is raised */
            poker.PlayGame();
        }

        void poker_UpdateWinnings(object sender, WinningsEventArgs e)
        {
            AddToCredits(e.Winnings);
        }

        public void AddToCredits(int winnings)
        {
            credits += winnings;
            labelWinnings.Text = credits.ToString();
        }
    }

    public class Poker
    {
        public event EventHandler<WinningsEventArgs> UpdateWinnings;

        public void PlayGame()
        {
            // ...
            // Simulate Winning
            OnUpdateWinnings(new WinningsEventArgs(1000));
        }

        protected virtual void OnUpdateWinnings(WinningsEventArgs e)
        {
            EventHandler<WinningsEventArgs> eh = UpdateWinnings;
            if (eh != null)
                eh(this, e);
        }
    }

    public class WinningsEventArgs : EventArgs
    {
        public WinningsEventArgs(int winnings)
        {
            Winnings = winnings;
        }

        public int Winnings
        {
            get;
            private set;
        }
    }
}

public class TestClass
{
    /// <summary>
    /// Field to hold class instance.
    /// </summary>
    private ClassWithEvent classWithEvent;

    /// <summary>
    /// Initializes a new intance of TestClass.
    /// </summary>
    public TestClass()
    {
        // Instanciate classWithEvent
        classWithEvent = new ClassWithEvent();
        // Subscribe to the classWithEvent.Event, the method in brackets will be called when it is raised
        classWithEvent.Event += new EventHandler(classWithEvent_Event);
    }

    /// <summary>
    /// Method called when classWithEvent.Event is raised
    /// </summary>
    /// <param name="sender">The ClassWithEvent instance that raised the event.</param>
    /// <param name="e">The EventArgs instance that was sent with the event.</param>
    void classWithEvent_Event(object sender, EventArgs e)
    {
        // Do what you need to do here!
        Console.WriteLine("Event Rased!");
    }
}

public class ClassWithEvent
{
    /// <summary>
    /// This is the event!
    /// </summary>
    public event EventHandler Event;

    /// <summary>
    /// This method actually raises the event.
    /// </summary>
    /// <param name="e">The arguments class that holds any data relating to the event.</param>
    protected virtual void OnEvent(EventArgs e)
    {
        // Create a copy...
        EventHandler eh = Event;
        // Null check as eh will be null if no subscribers
        if (eh != null)
            eh(this, e);
    }

    /// <summary>
    /// This public method is just by way of example. This could be any method, property setter etc...
    /// </summary>
    public void PerformEvent()
    {
        // Call the method that actually raises the event
        OnEvent(EventArgs.Empty);
    }
}

[DllImport("user32.dll", CallingConvention=CallingConvention.StdCall, SetLastError=true)]
public static extern IntPtr SendInput(int count, ref INPUT input, int size);

• It breaks the principles of client / server architecture. If you want to access a common object you should only do this on the server via method calls. There are several ways of persisting the common object between calls / clients
• By attempting to call methods/set properties on an object instanced on the server from the client, you are opening up a security hole