Public Class Form1
    Dim WithEvents Cb As New ComboBox With {.DrawMode = _
      DrawMode.OwnerDrawFixed, .Parent = Me}
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Cb.Items.AddRange({"White", "Black", "Red", "Green", "Blue"})
    End Sub
 
    Private Sub Cb_DrawItem(sender As Object, e As DrawItemEventArgs) Handles _
      Cb.DrawItem
        Dim txt As String = Cb.Items(e.Index).ToString
        e.DrawBackground()
        If Not e.State = DrawItemState.None Then
            e.Graphics.FillRectangle(Brushes.SkyBlue, e.Bounds)
            Cb.Text = txt
            Me.BackColor = Color.FromName(txt)
        End If
        e.Graphics.DrawString(txt, Font, Brushes.Black, e.Bounds)
    End Sub
End Class