Dim isInList As Boolean = Me.ComboBox1.Items.Contains(Me.ComboBox1.Text)

    Private Sub ComboBox1_TextChanged(ByVal sender As Object, ByVal e As _
      System.EventArgs) Handles ComboBox1.TextChanged
        Dim idx As Integer = Me.ComboBox1.FindString(Me.ComboBox1.Text)
        Dim pos As Integer = Me.ComboBox1.SelectionStart
        If Not Me.ComboBox1.Items.Count > 0 Then Return
        Me.ComboBox1.SelectedIndex = IIf(idx > -1, idx, 0)
        Me.ComboBox1.Select(pos, Me.ComboBox1.Text.Length - pos)
    End Sub