Option Explicit On : Option Strict On : Option Infer Off
Imports System.Windows.Forms
 
Public Class cCheckedListbox
    Inherits System.Windows.Forms.CheckedListBox
 
    Public Property Checked(ByVal Index As Integer) As Boolean
        Get
            Dim cs As CheckState = MyBase.GetItemCheckState(Index)
            If cs = CheckState.Indeterminate Then
                Throw New System.InvalidOperationException
            End If
            If cs = CheckState.Checked Then
                Return True
            Else
                Return False
            End If
        End Get
        Set(ByVal value As Boolean)
            MyBase.SetItemChecked(Index, value)
        End Set
    End Property
End Class

'Deklaration im Deklarationsteil der Form
Dim WithEvents clbo As New cCheckedListbox
 
'Zuordnung in der Form_Load-Routine
Me.Controls.Add(clbo)
 
'Und ab jetzt geht es mit ...
clbo.Items.Add("soso")
clbo.Items.Add("nono")
 
clbo.Checked(0) = True
If clbo.Checked(0) Then Stop