The method below belongs to a base class and gets fired alright.

Unfortunately I don't know how to render the checkbox in front of the item string.

   Protected Overrides Sub OnDrawItem(e As DrawItemEventArgs)
        e.DrawBackground()
        If e.State = DrawItemState.Focus Then
            e.DrawFocusRectangle()
        End If
        Dim index = e.Index
        If index < 0 OrElse index >= Items.Count Then
            Return
        End If
        Dim item = Items(index)
        Dim text As String
        text = If((item Is Nothing), "(null)", item.ToString())
        Using brush = New SolidBrush(e.ForeColor)
            e.Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit
            e.Graphics.DrawString(text, Me.Font, brush, e.Bounds)
        End Using
    End Sub