Hotfix information

File information

  Date         Time   Version        Size       File name
  ----------------------------------------------------------------------
  01-Dec-2004  04:08  1.1.4322.1090  1,703,936  System.Design.dll
  01-Dec-2004  04:04  1.1.4322.1090    466,944  System.Drawing.dll
  01-Dec-2004  04:13  1.1.4322.1090  2,048,000  System.Windows.Forms.dll

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Steps to reproduce the problem

1. Start Microsoft Visual Studio .NET 2003.
2. On the File menu, click New, and then click Project.
3. Click Visual C# Projects, click Windows Application, and then click OK.
4. In Solution Explorer, right-click Form1.cs, click View Code, and then replace all the code that is in Form1.cs with the following code.

   using System;
   using System.Drawing;
   using System.Collections;
   using System.ComponentModel;
   using System.Windows.Forms;
   using System.Data;
   
   namespace MDIMenuTest
   {
   	/// <summary>
   	/// Summary description for Form1.
   	/// </summary>
   	public class Form1 : System.Windows.Forms.Form
   	{
   		private System.Windows.Forms.MainMenu mainMenu1;
   		private System.Windows.Forms.MenuItem menuMain;
   		private System.Windows.Forms.MenuItem MenuFromMain;
   		/// <summary>
   		/// Required designer variable.
   		/// </summary>
   		private System.ComponentModel.Container components = null;
   
   		public Form1()
   		{
   			//
   			// Required for Windows Form Designer support
   			//
   			InitializeComponent();
   
   			// create new child
   			Child formChild = new Child();
   			formChild.MdiParent = this;   // set parent
   			formChild.Show();          // display child
   		}
   
   		/// <summary>
   		/// Clean up any resources being used.
   		/// </summary>
   		protected override void Dispose( bool disposing )
   		{
   			if( disposing )
   			{
   				if (components != null) 
   				{
   					components.Dispose();
   				}
   			}
   			base.Dispose( disposing );
   		}
   
   		#region Windows Form Designer generated code
   		/// <summary>
   		/// Required method for Designer support - do not modify
   		/// the contents of this method with the code editor.
   		/// </summary>
   		private void InitializeComponent()
   		{
   			this.mainMenu1 = new System.Windows.Forms.MainMenu();
   			this.menuMain = new System.Windows.Forms.MenuItem();
   			this.MenuFromMain = new System.Windows.Forms.MenuItem();
   			// 
   			// mainMenu1
   			// 
   			this.mainMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
   																					  this.menuMain});
   			// 
   			// menuMain
   			// 
   			this.menuMain.Index = 0;
   			this.menuMain.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
   																					 this.MenuFromMain});
   			this.menuMain.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
   			this.menuMain.Text = "Menu";
   			// 
   			// MenuFromMain
   			// 
   			this.MenuFromMain.Index = 0;
   			this.MenuFromMain.Text = "MenuFromMain";
   			// 
   			// Form1
   			// 
   			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
   			this.ClientSize = new System.Drawing.Size(292, 266);
   			this.IsMdiContainer = true;
   			this.Menu = this.mainMenu1;
   			this.Name = "Form1";
   			this.Text = "Form1";
   			this.Load += new System.EventHandler(this.Form1_Load);
   
   		}
   		#endregion
   
   		/// <summary>
   		/// The main entry point for the application.
   		/// </summary>
   		[STAThread]
   		static void Main() 
   		{
   			Application.Run(new Form1());
   		}
   
   		
   	}
   }
   

5. On the Project menu, click Add Windows Form, click Windows Form under Templates, name the form Child.cs, and then click Open.
6. In Solution Explorer, right-click Child.cs, click View Code, and then replace all the code that is in Child.cs with the following code.

   using System;
   
   using System.Drawing;
   
   using System.Collections;
   
   using System.ComponentModel;
   
   using System.Windows.Forms;
   
   using System.Diagnostics;
   
    
   
   namespace MDIMenuTest
   
   {
   
   	/// <summary>
   
   	/// Summary description for Child.
   
   	/// </summary>
   
   	public class Child : System.Windows.Forms.Form
   
   	{
   
   		private System.Windows.Forms.MainMenu mainMenu1;
   
   		private System.Windows.Forms.MenuItem menuMain;
   
   		private System.Windows.Forms.MenuItem MenuFromChild;
   
   		private System.Windows.Forms.MenuItem menuItem1;
   
   		/// <summary>
   
   		/// Required designer variable.
   
   		/// </summary>
   
   		private System.ComponentModel.Container components = null;
   
    
   
   		public Child()
   
   		{
   
   			//
   
   			// Required for Windows Form Designer support
   
   			//
   
   			InitializeComponent();
   
    
   
   			//
   
   			// TODO: Add any constructor code after InitializeComponent call
   
   			//
   
   		}
   
    
   
   		/// <summary>
   
   		/// Clean up any resources being used.
   
   		/// </summary>
   
   		protected override void Dispose( bool disposing )
   
   		{
   
   			if( disposing )
   
   			{
   
   				if(components != null)
   
   				{
   
   					components.Dispose();
   
   				}
   
   			}
   
   			base.Dispose( disposing );
   
   		}
   
    
   
   		#region Windows Form Designer generated code
   
   		/// <summary>
   
   		/// Required method for Designer support - do not modify
   
   		/// the contents of this method with the code editor.
   
   		/// </summary>
   
   		private void InitializeComponent()
   
   		{
   
   			this.mainMenu1 = new System.Windows.Forms.MainMenu();
   
   			this.menuMain = new System.Windows.Forms.MenuItem();
   
   			this.MenuFromChild = new System.Windows.Forms.MenuItem();
   
   			// 
   
   			// mainMenu1
   
   			// 
   
   			this.mainMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
   
   																					  this.menuMain});
   
   			// 
   
   			// menuMain
   
   			// 
   
   			this.menuMain.Index = 0;
   
   			this.menuMain.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
   
   																					 this.MenuFromChild,
   
   			});
   
   			this.menuMain.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
   
   			this.menuMain.Text = "Menu";
   
   			this.menuMain.Popup += new System.EventHandler(this.menuMain_Popup);
   
   			// 
   
   			// MenuFromChild
   
   			// 
   
   			this.MenuFromChild.Index = 0;
   
   			this.MenuFromChild.Text = "MenuFromChild";
   
    
   
   			// 
   
   			// Child
   
   			// 
   
   			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
   
   			this.ClientSize = new System.Drawing.Size(292, 266);
   
   			this.Menu = this.mainMenu1;
   
   			this.Name = "Child";
   
   			this.Text = "Child";
   
    
   
   		}
   
   		#endregion
   
    
   
   		private void menuMain_Popup(object sender, System.EventArgs e)
   
   		{
   
   			// The goal is to dynamically change the child menu items during run time.
   
   			// Then, the new child menu items will be merged into the MDI main menu automatically by the .NET Framework.
   
   			// However, the program crashed after trying to add the following menu item to the MDI menu.
   
   			MenuItem menuItem = new MenuItem("New Menu Item From Child");
   
   			this.menuMain.MenuItems.Add(menuItem);
   
   		}
   
   	}
   
   }

7. On the Debug menu, click Start to compile and then run the project.
8. In the new application, click any menu choice. You receive the following error message:
   Object reference not set to an instance of an object

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