Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim asm = System.Reflection.Assembly.GetExecutingAssembly
    Dim myTypes As Type() = asm.GetTypes()
    Dim frm As Form


    For Each t As Type In myTypes
        If t.IsSubclassOf(GetType(System.Windows.Forms.Form)) AndAlso TextBox1.Text = t.Name Then
            frm = CType(Activator.CreateInstance(t), Form)
            frm.Hide()

            Dim thisButtonName As String = TextBox3.Text ' This is the name of the button I'm looking for
            Dim thisButtonName2 As String = TextBox2.Text ' this is the new tag name for that button
            ' Loop all controls in this form
            For Each ctrl As Control In Controls
                ' Is this control a button
                If TypeOf (ctrl) Is Button Then
                    ' Is this the correct button
                    If CType(ctrl, Button).Name = thisButtonName Then
                        CType(ctrl, Button).Tag = thisButtonName2
                    End If
                End If
            Next
        End If
    Next

    TreeView1.Nodes.Clear()

    For Each formprop In My.Forms.GetType.GetProperties
        Dim node = Me.TreeView1.Nodes.Add(formprop.Name)
        Dim form As Form = CType(formprop.GetValue(My.Forms, Nothing), Form)
        ControlsTree(node, form.Controls)
    Next
End Sub