Busqueda de clientes con combobox

[HaverRamirez]

En MSDN esta este ejemplo ve la validación

Código vb:

Private Sub ListBox1_SelectedValueChanged(ByVal sender As Object, ByVal e As EventArgs)
        If ListBox1.SelectedIndex <> -1  Then
            textBox1.Text = ListBox1.SelectedValue.ToString()
            ' If we also wanted to get the displayed text we could use
            ' the SelectedItem item property:
            ' Dim s = CType(ListBox1.SelectedItem, USState).LongName
        End If
    End Sub 'ListBox1_SelectedValueChanged
 

ListBox1.SelectedIndex <> -1

http://msdn.microsoft.com/en-us/library/system.windows.forms.listcontrol.selectedvalue.asp x