Opening WinForm in Outlook 2003 VSTO Addin with Wordmail enabled

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I have been banging my head with this issues for sometime now. Can someone

PLEASE help??? When I create a commandbar on a new inspector window that uses

word mail, the form that opens doesn't fully load. I have done a lot of

research on this and I believe it is a threading issue because I create my

command bar in word which is subclassed into Outlook. When wordmail isn't

enabled the apartment state of the executing thread is STA and when wordmail

is enabled it is MTA. I have tried to use a delegate to instantiate the form

instead with no success. Below are a couple of relevant posts I have found.

mentions in one of these that he used several API calls to make

this work. Can someone please provide a working sample. If you need a sample

to reproduce I can provide one. I used the code sample to load wordmail

toolbars on the inspector_activate event. I added another windows project and

then tried to instantiate the form from my class. It never fully loads. Below

are some links I have found helpful.

Ken Slovak - [MVP - Outlook]

Andrew's post is more relevant to what you're talking about in cases of

managed code, what I was posting about relates mostly to working with VB6


For managed code you have to do thread context synchronization callbacks.

What you do is on NewExplorer() and NewInspector() event handlers you call

Windows.Forms.Application.DoEvents() to prime the message pump and then you

get the current thread context, which in that case is the context of the

main Outlook addin thread. You store that context so it's always available.

Then when you want to open a form you set up a callback to a procedure that

will run in the main thread context and pass your form name along to that


// In a class context where it will stay alive:

private static System.Threading.SynchronizationContext _syncContext = null;

In the main thread event handlers code something like this:

if (_syncContext == null)



if (System.Threading.SynchronizationContext.Current != null)


_syncContext = System.Threading.SynchronizationContext.Current;



Then when you want to show the form:

// whatever arguments you want to pass to the callback are added here

object[] args = { };

System.Threading.SendOrPostCallback callback =



if (callback != null)


System.Threading.SynchronizationContext context = Globals.SyncContext;

if (context != null)


context.Send(callback, args);


In this case Globals.SyncContext accesses the stored context.

callbackClass is where the callback function lives and it's named

callbackProcedure. That procedure is what displays the form and populates

any controls from the arguments passed to it. In that callback the argumens

are passed as (Object state) and are decoded there as follows:

object[] arguments = (object[])state;

Then that array has all the arguments passed to the callback.

Note that this is not necessary for Outlook 2007, only for WordMail in

earlier versions of Outlook.
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