Building a Class that Raises Events in a Specific or UI Thread

Public Class BackgroundWorkerThreadSafe 'System.Windows.Threading.Dispatcher may require you to Add a Reference to "WindowsBase" (yes that is a Dot.Net library)
    Inherits System.ComponentModel.BackgroundWorker
    Public Shadows Event ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs)
    Public Shadows Event RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs)
    Private m_ExplicitDispatcher As System.Windows.Threading.Dispatcher = Nothing

    Protected Overrides Sub OnProgressChanged(ByVal e As System.ComponentModel.ProgressChangedEventArgs)
        RaiseEventAndExecuteItInAnExplicitOrUIThread(ProgressChangedEvent, New Object() {Me, e}, m_ExplicitDispatcher)
    End Sub

    Protected Overrides Sub OnRunWorkerCompleted(ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs)
        RaiseEventAndExecuteItInAnExplicitOrUIThread(RunWorkerCompletedEvent, New Object() {Me, e}, m_ExplicitDispatcher)
    End Sub

    Public Sub New(ByVal ExplicitDispatcher As System.Windows.Threading.Dispatcher)
        MyBase.New()
        m_ExplicitDispatcher = ExplicitDispatcher
    End Sub

    Private Shared Sub RaiseEventAndExecuteItInAnExplicitOrUIThread(ByVal _event As System.MulticastDelegate, ByVal _ParamArray_args() As Object, ByVal ExplicitThreadSynchronizationDispatcher As System.Windows.Threading.Dispatcher)
        If Not _event Is Nothing Then
            If _event.GetInvocationList().Length > 0 Then
                Dim _sync As System.ComponentModel.ISynchronizeInvoke = Nothing
                For Each _delegate As System.MulticastDelegate In _event.GetInvocationList()
                    If ((ExplicitThreadSynchronizationDispatcher Is Nothing) AndAlso (_sync Is Nothing) AndAlso (GetType(System.ComponentModel.ISynchronizeInvoke).IsAssignableFrom(_delegate.Target.GetType())) AndAlso (Not _delegate.Target.GetType().IsAbstract)) Then
                        Try
                            _sync = CType(_delegate.Target, System.ComponentModel.ISynchronizeInvoke)
                        Catch ex As Exception
                            Diagnostics.Debug.WriteLine(ex.ToString())
                            _sync = Nothing
                        End Try
                    End If
                    If Not ExplicitThreadSynchronizationDispatcher Is Nothing Then
                        Try
                            ExplicitThreadSynchronizationDispatcher.Invoke(_delegate, _ParamArray_args)
                        Catch ex As Exception
                            Diagnostics.Debug.WriteLine(ex.ToString())
                        End Try
                    Else
                        If _sync Is Nothing Then
                            Try
                                _delegate.DynamicInvoke(_ParamArray_args)
                            Catch ex As Exception
                                Diagnostics.Debug.WriteLine(ex.ToString())
                            End Try
                        Else
                            Try
                                _sync.Invoke(_delegate, _ParamArray_args)
                            Catch ex As Exception
                                Diagnostics.Debug.WriteLine(ex.ToString())
                            End Try
                        End If
                    End If
                Next
            End If
        End If
    End Sub
End Class