C# Panel As MDI Container

Question

In C# i want to create a panel that has the properties of a MDI container ie. isMdiContainer = true.

I tried something like this

form.MDIParent = thi         


        

Answer 1

I used Mathias's answer above and was able to get rid of most of the issues raised in the comments. I created a helper class for the child forms as well, in case anyone wanted to use it and/or make it better.

    public class MdiClientPanel : Panel
{
    private MdiClient _ctlClient = new MdiClient();

    // Callback event when a child is activated
    public delegate void ActivateHandler(object sender, MdiClientForm child);
    public event ActivateHandler OnChildActivated;

    /// 

    /// The current active child form
    /// 
    public Form ActiveMDIWnd
    {
        get;
        set;
    }

    /// 

    /// List of available forms
    /// 
    public List ChildForms = new List();

    /// 

    /// Std constructor
    /// 
    public MdiClientPanel()
    {
        base.Controls.Add(_ctlClient);
    }

    private Form _mdiForm = null;
    public Form MdiForm
    {
        get
        {
            if (_mdiForm == null)
            {
                _mdiForm = new Form();
                // Set the hidden _ctlClient field which is used to determine if the form is an MDI form
                System.Reflection.FieldInfo field = typeof(Form).GetField("ctlClient", 
                    System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);

                field.SetValue(_mdiForm, _ctlClient);
            }
            return _mdiForm;
        }
    }

    private void InitializeComponent()
    {
        SuspendLayout();
        ResumeLayout(false);
    }

    /// 

    /// Add this Form to our list of children and set the MDI relationship up
    /// 
    /// The new kid
    /// The new kid
    public MdiClientForm AddChild(MdiClientForm child)
    {
        child.MyMdiContainer = this;
        child.MdiParent = MdiForm;
        ChildForms.Add(child);

        return child;
    }

    /// 

    /// The user sent a "restore" command, so issue it to all children
    /// 
    public void RestoreChildForms()
    {
        foreach (MdiClientForm child in ChildForms)
        {
            child.WindowState = FormWindowState.Normal;
            child.MaximizeBox = true;
            child.MinimizeBox = true;
        }
    }

    /// 

    /// Send the Activated message to the owner of this panel (if they are listening)
    /// 
    /// The child that was just activated
    public void ChildActivated(MdiClientForm child)
    {
        ActiveMDIWnd = child;

        if (OnChildActivated != null)
            OnChildActivated(this, child);
    }

    /// 

    /// The child closed so remove them from our available form list
    /// 
    /// The child that closed
    public void ChildClosed(MdiClientForm child)
    {
        ChildForms.Remove(child);
    }
}

/// 

/// A wrapper class for any form wanting to be an MDI child of an MDI Panel
/// 
public class MdiClientForm : Form
{
    /// 

    /// My parent MDI container
    /// 
    public MdiClientPanel MyMdiContainer { get; set; }

    /// 

    /// Standard Constructor
    /// 
    public MdiClientForm()
    {
        Activated += OnFormActivated;
        FormClosed += OnFormClosed;
    }

    /// 

    /// Reports back to the container when we close
    /// 
    void OnFormClosed(object sender, FormClosedEventArgs e)
    {
        MyMdiContainer.ChildClosed(this);
    }

    /// 

    /// Reports back to the parent container when we are activated
    /// 
    private void OnFormActivated(object sender, EventArgs e)
    {
        MyMdiContainer.ChildActivated(this);
    }
}