toolbar button Rated 4 out of 5 stars

It is very useful addon for me. But I would like it is more user friendly:

Is it possible to implement toolbar button for this function?

I only need this function for several e-mail messages, for all other messages I use other message body views.

A simple button with functionality:
- on first click it sets the View | Message Body As | All Body Parts message display mode
- on second click it sets original display mode used before.

Or, another possibility instead of toolbar button - but I am not sure if it is in the scope of add-ons, is to add a filter something like: "for all messages from sender@sender.org set the View | Message Body As | All Body". But this solution seems to me not possible because View | Message Body As settings is global and not per message, as far as I can see.