Bug: org-catch-invisible-edits still allows some invisible edits [9.1.9]

Bug: org-catch-invisible-edits still allows some invisible edits [9.1.9]

[Vlad Shcherbina]

Steps to reproduce:
1. runemacs.exe -Q
2. In the scratch buffer, M-x org-mode
3. M-: (setq org-catch-invisible-edits 'show-and-error)
    (could be also reproduced with 'smart)
4. Replace the content of the scratch buffer with the following:
* hello
** world
5. Position point at the end of "hello", press Tab to collapse.
So it looks like this:
* hello<point>...
6. Press Del.

Expected result:
Edit should be prevented because it deletes invisible character.

Actual result:
Edit is performed without any warning.
By the way, the editor ends up in corrupt state because the content
of the buffer is now "* hello** world", but it is displayed as
"* hello..." and you can't uncollapse it by pressing Tab anymore.

Version info:
GNU Emacs 26.2 (build 1, x86_64-w64-mingw32) of 2019-04-13
Org mode version 9.1.9 (release_9.1.0-65-g5e4542 @
c:/emacs/share/emacs/26.2/lips/org/)

Re: Bug: org-catch-invisible-edits still allows some invisible edits [9.1.9]

[Bruno Barbier]

Vlad Shcherbina <vlad.shcherbina@gmail.com> writes:

> Steps to reproduce:
> 1. runemacs.exe -Q
> 2. In the scratch buffer, M-x org-mode
> 3. M-: (setq org-catch-invisible-edits 'show-and-error)
>     (could be also reproduced with 'smart)
> 4. Replace the content of the scratch buffer with the following:
> * hello
> ** world
> 5. Position point at the end of "hello", press Tab to collapse.
> So it looks like this:
> * hello<point>...
> 6. Press Del.
>
> Expected result:
> Edit should be prevented because it deletes invisible character.
>
> Actual result:
> Edit is performed without any warning.
> By the way, the editor ends up in corrupt state because the content
> of the buffer is now "* hello** world", but it is displayed as
> "* hello..." and you can't uncollapse it by pressing Tab anymore.
>
> Version info:
> GNU Emacs 26.2 (build 1, x86_64-w64-mingw32) of 2019-04-13
> Org mode version 9.1.9 (release_9.1.0-65-g5e4542 @
> c:/emacs/share/emacs/26.2/lips/org/)


FWIW, I could reproduce using <deletechar> (bound to
delete-forward-char). Using DEL (bound to org-delete-backard-char),
everything works as expected.

 GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.4) of
 2019-04-22

 emacs -Q:
   Org mode version 9.1.9 (release_9.1.9-65-g5e4542 @
   /usr/share/emacs/26.1/lisp/org/)
  
 fully configured emacs:
   Org mode version 9.2.3 (release_9.2.3-10-g385955 @ ...)


Bruno