I have an Mdiform which with help of menustrip opens Form1.
From this form(Form1) I open another form i.e Form2.which I want also to be a part of my mdiform
I created property of mdiform and mapped it in my form2 when it loads.but still it does not become a part of mdiform.
Another problem is ,it keeps generating new instances of form2 whenever I again click button in form1,which is child of my mdiform.I want that only single instance of form2 should be visible.
I tried doing different ways but still generates new instances.
Can anyone explain this?
Thanks in advance

See if this helps to load Form2 from Form1, into the MDI Form.

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        With Form2
            .MdiParent = myCoolMDIform '// set the MDI Parent for the Form.
            .Show() '// Load the Form.
        End With
    End Sub
End Class

AndAlso, this to Not create a new.instance of Form2.

Public Class Form2

    Private Sub Form2_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        e.Cancel = True '// .Cancel closing the Form.
        Me.Hide() '// ...and .Hide it.:)
    End Sub
End Class

Sorry this does not give soliution to my problem.
I have a form which is a mdiparent form Nmaed as ParentMDIForm.The menustrip in it
opens another form that is studentform which child of parentmdiform.
i hav set it as this.mdiparent=this that works fine.but A button in studentform opens
Form3 which is giving problem.
On button_clcik in studform
code is
Form3 f3=new Form3();
f3.MdiParent=ParentMdiForm ----this is a from name of mdi form ,gives error
f3.show()
I tried by creating property of parent form in studform
then set it as
f3.MdiParent=parentfrm---this also gives object reference not set as error

not getting it

>>Form3 f3=new Form3();
That looks entirely like C#.code and will "ALWAYS" give you an error in VB.NET.

AndAlso, as soon as you declare as "New Form3", you will "ALWAYS" load a new.instance of a Form.

So you need to check if already an instance of form is opened or not.. u can use singleton pattern.

Try something like this..

Private Shared _Instance As Form2 = Nothing
Public Shared Function Instance() As Boolean
        If _Instance Is Nothing OrElse _Instance.IsDisposed = True Then
            _Instance = New Form2
            Return False
        End If
        _Instance.BringToFront()
        Return True
    End Function

In calling form write this

If Form2.Instance = False Then
            Form2.ShowDialog()
        End If

Code has solved my problem for creating single instance of open form but the form2 still
does not become a part of an mdiparent form.I tried in different ways as I mentioned with code earlier in my post, could you pls check that?
Thanks

before calling u need to set

If Form2.Instance = False Then
' here u need to set its parent form.
            Form2.ShowDialog()
        End If
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