Thanks for the link. The AddProgress event is working, but I am unable to cancel the operation.
 

 
I tried both of these handlers seperately:
 

                'AddHandler Zip.AddProgress, New EventHandler(Of AddProgressEventArgs)(AddressOf Zip_AddProgress)                    AddHandler Zip.AddProgress, AddressOf Zip_AddProgress

 

 

Private Sub Zip_AddProgress(ByVal sender As Object, ByVal e As AddProgressEventArgs)

 

    If bwBackup.CancellationPending Then e.Cancel = True 'If we press the stop button, invoke Cancel. RunWorkerCompleted will be called.        MsgBox("hi")

 

    Select Case e.EventType            Case ZipProgressEventType.Adding_Started                'code removed; update status label here.                Exit Select            Case ZipProgressEventType.Adding_AfterAddEntry                'code removed; update status label here.                'e.Cancel = True                Exit Select        End Select

 
End Sub
 

 
The labels update as expected, and the message box fires constantly, as I would expect it to. However, e.Cancel is not working. Bypassing the background worker and directly cancelling the operation in Adding_AfterAddEntry (now commented out), did not work either. The operation continues until the SaveProgress phase, where it is cancelled immediately due to the previous call to bwBackup.CancelAsync.