Open only one form in vb.net

[vidhyapriya]

Hi all,

I am developing windows application using vb.net. In form1 button click i am opening form2.i am using tab control in form2.when i click the button form2 will open again when i click the button form2 shouldn't open instead of that in tab control tab page will be added in one form.
i used the code

Dim f As Form2
        If Not IsNothing(f) Then
            If Not f.IsDisposed Then
                MessageBox.Show("Already Exists")
                f.Show()
            Else
                f = New Form2()
                f.Show()
            End If
        Else
            MessageBox.Show("New")
            f = New Form2()
            f.Show()
        End If

what i want to do more...i need correct coding..help me

[Shashi Sadasivan]

iterate through each form in Application.openForms
and check if the form is of Form2 type.
It it does not find any then open a new one, else you can show the form!

As per your code there is something with IsNothing(f) which I do not know what it stands for (unless its some vb .net specific thing)