Show MDIChild Form from another MDIChild Form

Question

Let’s I have MDIParentForm (Home), Child Form (Form1, Form2), Home has one Menu (Add) and Form1 has button (btnOk)

'''''Here is C# Code''''''

 public partial class Home : DevExpress.XtraBars.Ribbon.RibbonForm
{
    public Home()
    {
        InitializeComponent();
    }
    public void  CreateForm(Form frm)
    {
        frm.MdiParent = this;
        frm.WindowState = FormWindowState.Maximized;
        frm.Show();
    }
    private void btnAddForm_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e)
    {
        Form1 frm = new Form1();
        CreateForm(frm);
    }
}
//Up to this 1st level my code works fine.
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void btnDone_Click(object sender, EventArgs e)
    {
//From Here I am not able show the Form2.
        Home MDIParentForm = new Home();
        Form2 frm = new Form2();
        MDIParentForm.CreateForm(childForm);
    }
}

Action: On the click of Add Menu I used to open Form1 (It works fine) and on the click of btnOk I want to open Form2 (which is another MDIChild form).

Let me know how we can accomplish this task.

Answer 1

What you do is you create yet another instance of your MDI parent and you set the Form2 as a child of this newly created MDI parent. This is clearly wrong, you want both to be children of the very same parent.

Either do this directly:

private void btnDone_Click(object sender, EventArgs e)
{
    Form2 frm = new Form2();
    // both have the same MDI parent
    frm.MDIParent = this.MDIParent;
    frm.Show();
}

or, if you insist on reusing your CreateForm

private void btnDone_Click(object sender, EventArgs e)
{
    Form2 frm = new Form2();
    ((Home)this.MDIParent).CreateForm( frm );
}

Both approaches depend on this.MDIParent set in form1 and make sure the same instance is used for newly created form2.