Re: outline.el, killing, yanking, and invisibility

[Richard Stallman]

    My more general solution transfers the 'invisible text property of
    overlays on the killed text to a new overlay on the yanked text.

That seems like the right approach for making outline mode DTRT.
However, I see two drawbacks in the specifics.

1. It is undesirable to put a yank-handler on the text in the buffer.
You could add it when killing.

2. We try to avoid any use of advice within Emacs itself.
It would be much cleaner to add a new hook for this.

3. If the text is yanked in some other mode, this should discard the
invisibility properties (as it normally does), not preserve them in
any way.

4. It would perhaps be better to add a hook for yank for this.  It
would be cleaner overall than using the yank-handler property in this
peculiar way.