Public Class wTestTest
 
 
    Private mT1 As String
    Private mT2 As String
    Private mAA As String
    Private mBB As String
    Public Property T1() As String
        Get
            Return mT1
        End Get
        Set(ByVal value As String)
            mT1 = value
        End Set
    End Property
    Public Property T2() As String
        Get
            Return mT2
        End Get
        Set(ByVal value As String)
            mT2 = value
        End Set
    End Property
    Public Property T3(Key As String) As String
        Get
            Select Case Key
                Case "AA"
                    Return mAA
                Case "BB"
                    Return mBB
                Case Else
 
            End Select
 
            Return mT2
        End Get
        Set(ByVal value As String)
            Select Case Key
                Case "AA"
                    mAA = value
                Case "BB"
                    mBB = value
                Case Else
 
            End Select
        End Set
    End Property
End Class

 Dim ggg As New wTestTest    
 
Private Sub Form_Load(ByVal sender As Object, ByVal e As EventArgs) Handles _
  MyBase.Load
        Dim var As Object
 
        ggg.T1 = "1T"
        Try
 
            TextBox1.DataBindings.Add("Text", ggg, "T1", False, _
              DataSourceUpdateMode.OnPropertyChanged)
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
 
        var = ggg
    End Sub