Использование программно созданых контролов

Dim textbox As New TextBox With {.Top = top, .Left = 3, .Width = 215, .Tag = label.Text}
AddHandler textbox.TextChanged, AddressOf change_select_textbox
top += textbox.Height
.TabPages(3).Controls.Add(textbox)
 
Private Sub change_select_textbox(ByVal sender As Object, ByVal e As System.EventArgs)
msgbox(sender.Tag.ToString & " " & sender.Text, vbinformation)
End Sub

AddHandler textbox.TextChanged, AddressOf change_select_textbox

  Private Sub change_select_textbox(ByVal sender As Object, ByVal e As System.EventArgs)
    msgbox(sender.Tag.ToString & " " & sender.Text, vbinformation)
  End Sub
 
  Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim textbox As New TextBox With {.Top = Top + 10, .Left = 10, .Width = 215, .Tag = Label1.Text}
    AddHandler textbox.TextChanged, AddressOf change_select_textbox
    Top += textbox.Height
    Me.Controls.Add(textbox)
  End Sub

Option Strict On
Public Class Form1
 
    Private Sub change_select_textbox(ByVal sender As Object, ByVal e As System.EventArgs)
        MsgBox(sender.Tag.ToString & " " & sender.Text, vbInformation)
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim textbox As New TextBox With {.Top = Top + 10, .Left = 10, .Width = 215, .Tag = "asdas"}
        AddHandler textbox.TextChanged, AddressOf change_select_textbox
        Top += textbox.Height
        Me.Controls.Add(textbox)
    End Sub
End Class

    Private Sub change_select_textbox(ByVal sender As Object, ByVal e As System.EventArgs)
        MsgBox(DirectCast(sender, TextBox).Tag.ToString & " " & DirectCast(sender, TextBox).Text, vbInformation)
    End Sub