Classe NativeWindow

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace NativeWindowApplication
{

    // Summary description for Form1.
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
    publicclass Form1 : System.Windows.Forms.Form
    {
        private MyNativeWindowListener nwl;
        private MyNativeWindow nw;

        internalvoid ApplicationActivated(bool ApplicationActivated)
        {
            // The application has been activated or deactivated
            System.Diagnostics.Debug.WriteLine("Application Active = " + ApplicationActivated.ToString());
        }

        private Form1()
        {
            this.Size = new System.Drawing.Size(300, 300);
            this.Text = "Form1";

            nwl = new MyNativeWindowListener(this);
            nw = new MyNativeWindow(this);

        }

        // The main entry point for the application.
        [STAThread]
        staticvoid Main()
        {
            Application.Run(new Form1());
        }
    }

    // NativeWindow class to listen to operating system messages.
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
    internalclass MyNativeWindowListener : NativeWindow
    {

        // Constant value was found in the "windows.h" header file.
        privateconstint WM_ACTIVATEAPP = 0x001C;

        private Form1 parent;

        public MyNativeWindowListener(Form1 parent)
        {

            parent.HandleCreated += new EventHandler(this.OnHandleCreated);
            parent.HandleDestroyed += new EventHandler(this.OnHandleDestroyed);
            this.parent = parent;
        }

        // Listen for the control's window creation and then hook into it.internalvoid OnHandleCreated(object sender, EventArgs e)
        {
            // Window is now created, assign handle to NativeWindow.
            AssignHandle(((Form1)sender).Handle);
        }
        internalvoid OnHandleDestroyed(object sender, EventArgs e)
        {
            // Window was destroyed, release hook.
            ReleaseHandle();
        }
        [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
        protectedoverridevoid WndProc(ref Message m)
        {
            // Listen for operating system messagesswitch (m.Msg)
            {
                case WM_ACTIVATEAPP:

                    // Notify the form that this message was received.// Application is activated or deactivated, // based upon the WParam parameter.
                    parent.ApplicationActivated(((int)m.WParam != 0));

                    break;
            }
            base.WndProc(ref m);
        }
    }

    // MyNativeWindow class to create a window given a class name.
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
    internalclass MyNativeWindow : NativeWindow
    {

        // Constant values were found in the "windows.h" header file.
        privateconstint WS_CHILD = 0x40000000,
                          WS_VISIBLE = 0x10000000,
                          WM_ACTIVATEAPP = 0x001C;

        privateint windowHandle;

        public MyNativeWindow(Form parent)
        {

            CreateParams cp = new CreateParams();

            // Fill in the CreateParams details.
            cp.Caption = "Click here";
            cp.ClassName = "Button";

            // Set the position on the form
            cp.X = 100;
            cp.Y = 100;
            cp.Height = 100;
            cp.Width = 100;

            // Specify the form as the parent.
            cp.Parent = parent.Handle;

            // Create as a child of the specified parent
            cp.Style = WS_CHILD | WS_VISIBLE;

            // Create the actual windowthis.CreateHandle(cp);
        }

        // Listen to when the handle changes to keep the variable in sync
        [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
        protectedoverridevoid OnHandleChange()
        {
            windowHandle = (int)this.Handle;
        }

        [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
        protectedoverridevoid WndProc(ref Message m)
        {
            // Listen for messages that are sent to the button window. Some messages are sent// to the parent window instead of the button's window.switch (m.Msg)
            {
                case WM_ACTIVATEAPP:
                    // Do something here in response to messagesbreak;
            }
            base.WndProc(ref m);
        }
    }
}

package NativeWindowApplication;

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;
import System.Runtime.InteropServices.*;
import System.Security.Permissions.*;

// Summary description for Form1.

public class Form1 extends System.Windows.Forms.Form
{
    private MyNativeWindowListener nwl;
    private MyNativeWindow nw;

    void ApplicationActived(boolean applicationActivated)
    {
        // The application has been activated or deactivated
        System.Diagnostics.Debug.WriteLine("Application Active = " 
            + Convert.ToString(applicationActivated));
    } //ApplicationActived

    public Form1()
    {
        this.set_Size(new System.Drawing.Size(300, 300));
        this.set_Text("Form1");

        nwl = new MyNativeWindowListener(this);
        nw = new MyNativeWindow(this);
    } //Form1

    // The main entry point for the application.
    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        Application.Run(new Form1());
    } //main
} //Form1

// NativeWindow class to listen to operating system messages.
/** @attribute SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.UnmanagedCode)
 */
public class MyNativeWindowListener extends NativeWindow
{
    // Constant value was found in the "windows.h" header file.
    private int WM_ACTIVATEAPP = 0x1C;
    private Form1 parent;

    public MyNativeWindowListener(Form1 parent)
    {
        parent.add_HandleCreated(new EventHandler(this.OnHandleCreated));
        parent.add_HandleDestroyed(new EventHandler(this.OnHandleDestroyed));
        this.parent = parent;
    } //MyNativeWindowListener

    // Listen for the control's window creation and then hook into it.
    void OnHandleCreated(Object sender, EventArgs e)
    {
        // Window is now created, assign handle to NativeWindow.
        AssignHandle(((Form1)sender).get_Handle());
    } //OnHandleCreated

    void OnHandleDestroyed(Object sender, EventArgs e)
    {
        // Window was destroyed, release hook.
        ReleaseHandle();
    } //OnHandleDestroyed

    protected void WndProc(Message m)
    {
        // Listen for operating system messages
        if (m.get_Msg() == WM_ACTIVATEAPP) {
            // Notify the form that this message was received.
            // Application is activated or deactivated, 
            // based upon the WParam parameter.
            parent.ApplicationActived(m.get_WParam().ToInt32() != 0);
        }
        super.WndProc(m);
    } //WndProc
} //MyNativeWindowListener

// MyNativeWindow class to create a window given a class name.
/** @attribute SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.UnmanagedCode)
 */
public class MyNativeWindow extends NativeWindow
{
    // Constant values were found in the "windows.h" header file.
    private int WS_CHILD = 0x40000000;
    private int WS_VISIBLE = 0x10000000;
    private int WM_ACTIVATEAPP = 0x1C;
    private int windowHandle;

    public MyNativeWindow(Form parent)
    {
        CreateParams cp = new CreateParams();

        // Fill in the CreateParams details.
        cp.set_Caption("Click here");
        cp.set_ClassName("Button");

        // Set the position on the form
        cp.set_X(100);
        cp.set_Y(100);
        cp.set_Height(100);
        cp.set_Width(100);

        // Specify the form as the parent.
        cp.set_Parent(parent.get_Handle());

        // Create as a child of the specified parent
        cp.set_Style(WS_CHILD | WS_VISIBLE);

        // Create the actual window
        this.CreateHandle(cp);
    } //MyNativeWindow

    // Listen to when the handle changes to keep the variable in sync
    protected void OnHandleChange()
    {
        windowHandle = this.get_Handle().ToInt32();
    } //OnHandleChange

    protected void WndProc(Message m)
    {
        // Listen for messages that are sent to the button window. 
        // Some messages are sent to the parent window 
        // instead of the button's window.
        if (m.get_Msg() == WM_ACTIVATEAPP) {
            // Do something here in response to messages
        }
        super.WndProc(m);
    } //WndProc
} //MyNativeWindow