Dim TextBoxList As New List(Of TextBox)
 
Private Sub TextBoxList_MouseDown(ByVal sender As Object, _
        ByVal e As System.Windows.Forms.MouseEventArgs)
    If TypeOf sender Is TextBox Then
       Dim tboCalling As TextBox = CType(sender, TextBox)
       tboCalling.BackColor = Color.Blue
    End If
End Sub
 
Private Sub Button1_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles Button1.Click
 
      For i As Integer = 1 To 10
         Dim TextBoxToList As New TextBox
         TextBoxList.Add(TextBoxToList)
         TextBoxToList.Parent = GroupBox1
 
         With TextBoxToList
            .Location = New System.Drawing.Point(20, 30 * i)
            .Width = 200
            .Name = "TextBox" & CStr(i)
            .Text = .Name
            AddHandler TextBoxToList.MouseDown, AddressOf TextBoxList_MouseDown
         End With
      Next i
 
        '...
End Sub