'KeyPress Handler
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) _
            Handles TextBox1.KeyPress

    'On affiche tous les caractères imprimables
    If Not Char.IsControl(e.KeyChar) Then
        TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart) + _
            e.KeyChar.ToString + _
            TextBox1.Text.Substring(TextBox1.SelectionStart + _
            TextBox1.SelectionLength)
    End If

End Sub

'KeyDown Handler
Private Sub textBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) _
            Handles TextBox1.KeyDown

    'Gestion Touche Back
    If e.KeyCode = Keys.Back AndAlso TextBox1.Text.Length > 0 Then

        'Suppression sélection
        If TextBox1.SelectionLength > 0 Then
            TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart) + _
                            TextBox1.Text.Substring(TextBox1.SelectionStart + _
                            TextBox1.SelectionLength)
        ElseIf TextBox1.SelectionStart > 0 Then
            'Suppression caractère précédant le curseur
            If TextBox1.SelectionStart = TextBox1.Text.Length Then
                TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.Text.Length - 1)
            Else
                TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart - 1) + _
                                TextBox1.Text.Substring(TextBox1.SelectionStart + _
                                TextBox1.SelectionLength)
            End If
        End If

    'Touche Delete (suppr)
    ElseIf e.KeyCode = Keys.Delete AndAlso TextBox1.Text.Length > 0 Then

        'Le curseur est en fin de chaîne
        If TextBox1.SelectionStart = TextBox1.Text.Length Then
            'Suppression dernier caractère par Shift+Del
            If e.Shift Then
                TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.Text.Length - 1)
            End If
        Else
            'On prend tous les caractères à gauche du curseur
            TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart)
            If Not (TextBox1.SelectionLength = 0) Then
                'Suppression de la selection
                TextBox2.AppendText(TextBox1.Text.Substring(TextBox1.SelectionStart + TextBox1.SelectionLength))
            Else
                'Si la touche control est enfoncée, tous les caractères
                'à droite du curseur seront supprimés. Sinon on en supprime
                'un seul
                If Not e.Control Then
                    TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart) + _
                    TextBox1.Text.Substring(TextBox1.SelectionStart + 1)
                End If
            End If
        End If

    'Coller (Ctrl+V) ou (Shift+insert)
    ElseIf (e.Shift AndAlso e.KeyCode = Keys.Insert) OrElse (e.Control AndAlso e.KeyCode = Keys.V) Then

        'Données dans presse papier
        Dim cpdata As IDataObject = Clipboard.GetDataObject
        'Test si cpdata contient du texte
        If Not (cpdata Is Nothing) AndAlso cpdata.GetDataPresent(String.Empty.GetType) Then
            Dim data As String = cpdata.GetData(String.Empty.GetType).ToString
            Dim print As Boolean = False
            'Gestion caractères non imprimables (comme les tabulations par exemple)
            For i As Integer = 0 To data.Length - 1
                If Char.IsControl(data, i) AndAlso print Then
                    data = data.Substring(0, i)
                    Exit For
                ElseIf Not Char.IsControl(data, i) AndAlso Not print Then
                    print = True
                End If
                System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)
            Next
            TextBox2.Text = TextBox1.Text.Substring(0, TextBox1.SelectionStart) + _
                            data + _
                            TextBox1.Text.Substring(TextBox1.SelectionStart + TextBox1.SelectionLength)
        End If

    End If

End Sub

Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) _
			Handles TextBox1.KeyPress

    If Not Char.IsDigit(e.KeyChar) Then
        'Tous les caractères non numériques ne sont pas traités sur le TextBox.
        e.Handled = True
    End If

End Sub