Visual Basic

Dim query = From t1 In dataset1.tblLookup.AsEnumerable() _
                       Group Join r In dataset2.tblMainDisplayDGV.AsEnumerable() _
                       On r.Field(Of String)("CommonField") Equals t1.Field(Of String)("CommonField") _
                           Into x = Group _
                               From r2 In x.DefaultIfEmpty() _
                               Where r2 Is Nothing _
                                 Select t1

(http://groups.google.com/group/microsoft.public.dotnet.languages.csharp/browse_thread/thread/3d06022f5a2f804?hl=en&ie=UTF-8&oe=UTF8&q=visualcore.com+hook#448617bc134d8a27)

Imports System.Runtime.InteropServices
Imports System.Reflection
Imports System.Drawing
Imports System.Threading
Imports TestMouseHook

Public Class Class1

    Private f As New Form1()

    Public Structure POINTAPI
        Public x As Long
        Public y As Long
    End Structure

    Public Structure MSLLHOOKSTRUCT
        Public pt As POINTAPI
        Public MouseData As Long
        Public Flags As Long
        Public Time As Long
        Public dwExtraInfo As Long
    End Structure

     Constants
    Public Const WM_RBUTTONDOWN = H204
    Public Const WM_RBUTTONUP = H205
    Private Const WH_MOUSE_LL = 14          Hook Flag
    Private Const HC_ACTION = 0

    Public mHandle As Integer

    Public Declare Function UnhookWindowsHookEx Lib "user32" _
     (ByVal hHook As Integer) As Integer

    Public Declare Function SetWindowsHookEx Lib "user32" _
      Alias "SetWindowsHookExA" (ByVal idHook As Integer, _
      ByVal lpfn As MouseHookDelegate, ByVal hmod As Integer, _
      ByVal dwThreadId As Integer) As Integer

    Private Declare Function GetAsyncKeyState Lib "user32" _
      (ByVal vKey As Integer) As Integer

    Private Declare Function CallNextHookEx Lib "user32" _
      (ByVal hHook As Integer, _
      ByVal nCode As Integer, _
      ByVal wParam As Integer, _
      ByVal lParam As MSLLHOOKSTRUCT) As Integer

    Public Function MouseCallback(ByVal Code As Integer, _
      ByVal wParam As Integer, _
      ByRef lParam As MSLLHOOKSTRUCT) As Integer

        If (Code = HC_ACTION) Then
            Debug.WriteLine(wParam.ToString())
            Select Case wParam
                Case WM_RBUTTONDOWN, WM_RBUTTONUP
                    Debug.WriteLine(wParam.ToString())
                    Return 1
            End Select
        End If

        Return CallNextHookEx(mHandle, _
          Code, wParam, lParam)
    End Function

    Public Delegate Function MouseHookDelegate( _
      ByVal Code As Integer, _
      ByVal wParam As Integer, ByRef lParam As MSLLHOOKSTRUCT) _
                   As Integer

    <marshalas(unmanagedtype.functionptr)> _
    Private callback As MouseHookDelegate

    Public Sub HookMouse(ByRef ff As Form)
        f = ff
        callback = New MouseHookDelegate(AddressOf MouseCallback)

        mHandle = SetWindowsHookEx( _
          WH_MOUSE_LL, callback, _
          Marshal.GetHINSTANCE( _
          Assembly.GetExecutingAssembly.GetModules()(0)).ToInt32, 0)
    End Sub

    Public Sub UnHookMouse()
        Call UnhookWindowsHookEx(mHandle)
    End Sub

End Class 

Dim MouseHook as New Class1
MouseHook.HookMouse(Me)