Private Sub FindStringButton_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles FindStringButton.Click
        Dim index As Integer = ComboBox1.FindString(TextBox1.Text)
        If (index < 0) Then
            MessageBox.Show("Item not found.")
            TextBox1.Text = String.Empty
        Else
            ComboBox1.SelectedIndex = index
        End If
    End Sub