Implementing the IAutoComplete2 Interface in Vb.Net

[dynamic_sysop]

I've been teaching myself a bit about Interfaces for a little while and decided to try to create a vb.net version of the IAutoComplete2 interface.
you can see info on this for C++ on msdn.
this example implements autocomplete on an given array of strings ( eg: in a listbox , combobox etc... )

Private autoComp As AutoComplete

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'/// add autocomlete to an array of strings, in this case a listbox
autoComp = New AutoComplete(TextBox1.Handle, ArrayList.Adapter(ListBox1.Items))
'/// enable autocomplete
autoComp.Enable()

End Sub
End Class

#Region " AutoComplete Class "

Public Class AutoComplete
Implements IDisposable

Private autoComp As Type
Private objAutoComp As IAutoComplete

Public Sub New(ByVal hwndEdit As IntPtr, ByVal strList As ArrayList, Optional ByVal pwszRegKeyPath As String = Nothing, Optional ByVal pwszQuickComplete As String = Nothing)
Dim iEnumList As New EnumString()
iEnumList.strArray = strList

autoComp = Type.GetTypeFromCLSID(New Guid("{00BB2763-6A77-11D0-A535-00C04FD7D062}"))
objAutoComp = DirectCast(Activator.CreateInstance(autoComp), IAutoComplete)

'/// initialize IAutoComplete
objAutoComp.Init(hwndEdit, iEnumList, pwszRegKeyPath, pwszQuickComplete)
'/// set IAutoComplete Options
objAutoComp.SetOptions(Convert.ToUInt32(ShowOptions.ACO_AUTOSUGGEST Or ShowOptions.ACF_UPDOWNKEYDROPSLIST Or ShowOptions.ACO_AUTOAPPEND))
'/// Enable IAutoComplete
objAutoComp.Enable(True)

End Sub

Public Sub Dispose() Implements System.IDisposable.Dispose
Me.ReleaseComObject = Marshal.ReleaseComObject(objAutoComp)
End Sub

Private WriteOnly Property ReleaseComObject()
Set(ByVal Value)
Me.ReleaseComObject = Value
End Set
End Property

Public Sub Disable()
objAutoComp.SetOptions(Convert.ToUInt32(ShowOptions.ACO_NONE))
End Sub

Public Sub Enable()
objAutoComp.SetOptions(Convert.ToUInt32(ShowOptions.ACO_AUTOSUGGEST Or ShowOptions.ACF_UPDOWNKEYDROPSLIST Or ShowOptions.ACO_AUTOAPPEND))
End Sub

End Class

#End Region


#Region " IAutoComplete2 Interface "

<ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("EAC04BC0-3791-11D2-BB95-0060977B464C")> _
Public Interface IAutoComplete

Function Init(ByVal hwndEdit As IntPtr, <MarshalAs(UnmanagedType.IUnknown)> ByVal punkACL As Object, ByVal pwszRegKeyPath As String, ByVal pwszQuickComplete As String) As Int32
'/// we must use <PreserveSig()> _ otherwise after using autocomplete , fields will not return the next time
<PreserveSig()> _
Function Enable(<[In]()> ByVal fEnable As Boolean) As Boolean
<PreserveSig()> _
Function SetOptions(<[In]()> ByVal dwFlag As UInt32) As Integer
<PreserveSig()> _
Function GetOptions(<Out()> ByRef pdwFlag As UInt32) As Integer

End Interface

#End Region

#Region " IEnumString Interface "
'/// HKEY_CLASSES_ROOT\Interface\{00000101-0000-0000-C000-000000000046}\IEnumString
<ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00000101-0000-0000-C000-000000000046")> _
Public Interface IEnumString

Function [Next](ByVal celt As Integer, ByVal rgelt() As String, ByRef pceltFetched As Integer) As Integer
Function Skip(ByVal celt As Integer) As Integer
Function Reset() As Integer
Sub Clone(ByRef ppenum As IEnumString)

End Interface

#End Region

#Region " IEnumString Class "

Public Class EnumString
'/// UCOMIEnumString is the same as the IEnumString interface
'/// see more at Msdn on http://msdn.microsoft.com/library/default.asp?url=/library/en-us/com/htm/cmi_d2l_89uv.asp
Implements UCOMIEnumString

Public strArray As ArrayList
Private Pos As Integer = 0

Public Function [Next](ByVal celt As Integer, ByVal rgelt As String(), ByRef pceltFetched As Integer) As Integer Implements UCOMIEnumString.Next
Dim retval As Integer = 1
pceltFetched = 0
While Not Pos = strArray.Count AndAlso Not pceltFetched = celt
rgelt(pceltFetched) = strArray(Pos)
pceltFetched += 1
Pos += 1
End While

If Not pceltFetched.CompareTo(celt) = -1 Then
retval = 0
End If

Return retval

End Function

Public Function Skip(ByVal celt As Integer) As Integer Implements UCOMIEnumString.Skip
Dim retval As Integer = 1
Pos += celt

If Not Pos = strArray.Count Then
retval = 0
End If

Return retval
End Function

Public Function Reset() As Integer Implements UCOMIEnumString.Reset
Pos = 0
Return Pos
End Function


Public Sub Clone(ByRef ppenum As UCOMIEnumString) Implements UCOMIEnumString.Clone
'/// create a Clone of this Class
ppenum = DirectCast(Me, EnumString)
End Sub

End Class

#End Region

#Region " AutoComplete Show Options Enums "

Public Enum ShowOptions
ACO_NONE = 0
ACO_AUTOSUGGEST = &H1
ACO_AUTOAPPEND = &H2
ACO_SEARCH = &H4
ACO_FILTERPREFIXES = &H8
ACO_USETAB = &H10
ACF_UPDOWNKEYDROPSLIST = &H20
ACO_RTLREADING = &H40
End Enum

#End Region

included as always a sample project...