ToolbarControl MDI application
ChildForm.cs
// Copyright 2010 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using ESRI.ArcGIS.Controls;
using System.Windows.Forms;

namespace MDIApplication
{
  public class ChildForm : System.Windows.Forms.Form
  {
    private System.ComponentModel.Container components = null;
    private const int WM_ENTERSIZEMOVE = 0x231;
    private ESRI.ArcGIS.Controls.AxMapControl axMapControl1; //For resizing
    private const int WM_EXITSIZEMOVE = 0x232;  //For resizing

    public ChildForm()
    {
      InitializeComponent();
    }

    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()
    {
      System.Resources.ResourceManager resources = new System.Resources.ResourceManager(typeof(ChildForm));
      this.axMapControl1 = new ESRI.ArcGIS.Controls.AxMapControl();
      ((System.ComponentModel.ISupportInitialize)(this.axMapControl1)).BeginInit();
      this.SuspendLayout();
      // 
      // axMapControl1
      // 
      this.axMapControl1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
        | System.Windows.Forms.AnchorStyles.Left) 
        | System.Windows.Forms.AnchorStyles.Right)));
      this.axMapControl1.Location = new System.Drawing.Point(0, 0);
      this.axMapControl1.Name = "axMapControl1";
      this.axMapControl1.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("axMapControl1.OcxState")));
      this.axMapControl1.Size = new System.Drawing.Size(376, 272);
      this.axMapControl1.TabIndex = 0;
      this.axMapControl1.OnMapReplaced += new ESRI.ArcGIS.Controls.IMapControlEvents2_Ax_OnMapReplacedEventHandler(this.axMapControl1_OnMapReplaced);
      // 
      // ChildForm
      // 
      this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
      this.ClientSize = new System.Drawing.Size(376, 270);
      this.Controls.Add(this.axMapControl1);
      this.Name = "ChildForm";
      this.ShowInTaskbar = false;
      this.Text = "MDIChild";
      this.Load += new System.EventHandler(this.ChildForm_Load);
      ((System.ComponentModel.ISupportInitialize)(this.axMapControl1)).EndInit();
      this.ResumeLayout(false);

    }
    #endregion

    private void ChildForm_Load(object sender, System.EventArgs e)
    {
      //Suppress drawing while resizing
      this.SetStyle(ControlStyles.EnableNotifyMessage,true);
      axMapControl1.BorderStyle =  esriControlsBorderStyle.esriNoBorder;
    }

    protected override void OnNotifyMessage(System.Windows.Forms.Message m)
    {
      /*This method of suppressing resize drawing works by examining the windows messages 
      sent to the form. When a form starts resizing, windows sends the WM_ENTERSIZEMOVE 
      Windows(message). At this point we suppress drawing to the MapControl and 
      PageLayoutControl and draw using a "stretchy bitmap". When windows sends the 
      WM_EXITSIZEMOVE the form is released from resizing and we resume with a full 
      redraw at the new extent.

      Note in DotNet forms we can not simply use the second parameter in a Form_Load 
      event to automatically detect when a form is resized as follows:
      AxPageLayoutControl1.SuppressResizeDrawing(False, Me.Handle.ToInt32)
      This results in a System.NullException when the form closes (after layers have been 
      loaded). This is a limitation caused by .Net's particular implementation of its 
      windows message pump which conflicts with "windows subclassing" used to watch the
      forms window.*/

      base.OnNotifyMessage (m);
      
      if (m.Msg == WM_ENTERSIZEMOVE)
      {
        axMapControl1.SuppressResizeDrawing(true, 0);
      }
      else if (m.Msg == WM_EXITSIZEMOVE)
      {
        axMapControl1.SuppressResizeDrawing(false, 0);
      }
    }

    private void axMapControl1_OnMapReplaced(object sender, ESRI.ArcGIS.Controls.IMapControlEvents2_OnMapReplacedEvent e)
    {
      //Set the forms text
      this.Text = "MDIChild (" + axMapControl1.DocumentFilename + ")";
    }

  }
}