Err.Number and it's relationship to HResult?

[TrtnJohn]

I've recently converted some VB 6 code over that used the old non-structured
exception handling. I also have some .NET classes that raise custom
exception classes. When the code was VB6 I used to expose my .NET classes
using COM interop and errors raised from .NET classes were being caught
correctly in VB6. Now that everything is .NET the old non-structured
exception handling is still there in the converted classes. But now the
Err.Number is not reflecting the HResult of the error raised. I wrote a
simple little Windows Application form with 2 buttons to simulate the
problem. Here is the code snippet:

Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click
On Error GoTo ErrHandler
Err.Description = "Test Error"
Err.Raise(-2147215379)
Exit Sub

ErrHandler:
MsgBox(Err.Numb er & " : " & Err.Description )
End Sub

Private Sub Button2_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button2.Click
Try
Throw New TestException
Catch ex As Exception
MsgBox(Err.Numb er & " : " & Err.Description )
End Try
End Sub

Private Class TestException
Inherits ApplicationExce ption

Public Sub New()
MyBase.New()
MyBase.HResult = -2147215379
End Sub

Public Overrides ReadOnly Property Message() As String
Get
Return "Test Exception"
End Get
End Property
End Class

If you click Button1 you get the follwoing message:

-2147215379 : Test Error

If you click Button2 you get the following message:

5 : Test Exception