BUG: Command events fired only to last addin loaded in Visual Studio .NET

Author:	Carlos J. Quintero (Microsoft MVP)	Applies to:	Microsoft Visual Studio .NET 2002
Date:	April 2004		Microsoft Visual Studio .NET 2003

Introduction

When two add-ins set event handlers to the same command of the Visual Studio .NET IDE, only the last one loaded receives events from that command.

Cause

This is a bug of Visual Studio .NET.

More Information

Steps to reproduce the problem:

Create two add-ins with the code (VB.NET) below. Each add-in shows a message when connected and each one should show a message when the user clicks the Help \ About menu. However, only the last loaded add-in shows the second message.

Private m_objAddIn As AddIn
Private WithEvents m_objAboutCommandEvents As EnvDTE.CommandEvents

Public Sub OnConnection(ByVal application As Object, _
   ByVal connectMode As Extensibility.ext_ConnectMode, _
   ByVal addInInst As Object, ByRef custom As System.Array) _
   Implements Extensibility.IDTExtensibility2.OnConnection

   Dim objDTE As EnvDTE.DTE
   Dim objCommand As Command

   objDTE = CType(application, EnvDTE.DTE)
   m_objAddIn = CType(addInInst, EnvDTE.AddIn)
   objCommand = objDTE.Commands.Item("Help.About")
   m_objAboutCommandEvents = objDTE.Events.CommandEvents(objCommand.Guid, objCommand.ID)

   MessageBox.Show("Addin " & m_objAddIn.Name & " connected")

End Sub

Private Sub m_objAboutCommandEvents_BeforeExecute(ByVal Guid As String, ByVal ID As Integer, _
   ByVal CustomIn As Object, ByVal CustomOut As Object, ByRef CancelDefault As Boolean) _
   Handles m_objAboutCommandEvents.BeforeExecute

   MessageBox.Show("Before showing about window from addin " & m_objAddIn.Name)

End Sub

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