Thank you so much Guessed, that's very nice of you!

I'll see if it could be from what you indicate, if not also see if I can't find something in the RibbonX book.

If I have the solution I will indicate it after the post.

Have a nice day,
David

PS: however I have the impression that it comes from the ribbon object, as if the 2, 3... documents opened on the same workstation, shared only one instance instead of having each one its own.