Public Shared frmMain As Form1

    frmMain = Me

    Form1.frmMain.TextBox1 = "Von Form2!"

Module Module1
    Public frmMain As Form1
    Public Sub main()
        frmMain = New Form1()
        frmMain.ShowDialog()
    End Sub
End Module

    frmMain.TextBox1 = "Von Form2!"

    CType(Owner,Form1).TextBox1.Text =

    Dim f As New Form2(Me)
    f.Show()