I have a question about something I looked into a little while ago, then
abandoned, and now would like to come back to.

I would like to create an object that can be embedded in Word, Excel
(ppt?) very similarly to how a bitmap can be embedded. I want for a
user to be able to insert the object, then be able to double-click on it
to edit in the object's own application (a custom application I would
also write). The object needs to be able to store state so that when
users come back to it they can edit it further.

What is the best way to go about doing this? I believe this is
OLE/ActiveX technology, which I know is elderly and possibly discouraged
now. I would prefer to develop in .NET, but it doesn't seem to have
such capabilities. I see in VSTO 2005 the ActionPane object, but this
really doesn't seem to allow for quite what I would like to do.

Perhaps I am missing something--I welcome any and all insights to this
end. How do I go about creating this embeddable object?

Thanks for your help!