Private Sub CommandButton1_Click()
' Test si vide
If Me.TextBox1 = "" Then
Me.TextBox1.SetFocus
Exit Sub
End If
'Test si existe
On Error Resume Next
Me.ListBox1 = Me.TextBox1
On Error GoTo 0
If Me.ListBox1.ListIndex = -1 Then
Me.ListBox1.AddItem Me.TextBox1
End If
Me.ListBox1.ListIndex = -1
Me.TextBox1 = ""
Me.TextBox1.SetFocus
End Sub