@update! Lately the addon was updated and should work in Facebook too! Some fixes were made so overall behaviour should be more robust.

Original answer below.

Hello! Thank you for your comment! :)

The options page was available by Firefox' options menu and I have made it accessible through the context menu. There you can edit and add new notes (improvements added in the current version).

As for input fields that refuse the input: unfortunately I can't find out how to support non-standard input fields like Facebook Messenger ones.
Instead of trying to place the note in such weird places now it's copied to clipboard so it can be easily pasted by CTRL+V. I hope it works for you!


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Why won't they work?
There are no real input fields (as in html tag) but heavily scripted editable fields. When I try to programmatically modify the field, Facebook's scripts override them with the old value.

I have even tried to write the note into such field letter by letter and fire keyboard events after each one. I have hoped that it would make Facebook think that the letter was added by a normal keyboard input but that didn't work either. I have no idea for any workaround now.