Re: New package `outline-occur'

 > So the new variable should be like display-buffer-alist
 > (and use the same display-buffer-assq-regexp) whereas
 > display-buffer-alist is indented for user customization,
 > but the new variable is for applications to let-bind it.
 > Maybe a new app-action after user-action:
 >
 > - display-buffer-overriding-action
 > - user-action (by display-buffer-assq-regexp)
 > - app-action (by display-buffer-assq-regexp)
 > - special-action
 > - action
 > - extra-action
 > - display-buffer-base-action
 > - display-buffer-fallback-action
 >
 > This will allow overriding actions only for some categories
 > like was necessary for bug#81233, etc.

I could imagine calling it 'display-buffer-action-alist' but I gradually
lost control over 'display-buffer' in the past years.  We still carry on
things like the 'special-display-...' stuff (obsolete since 24.3) and
the old FRAME argument we handle in "extra-action".  For example,
"special-action" is a user customization so "app-action" should probably
not override it.

Using 'buffer-match-p' together with 'category' and 'this-command' has
slowly defied any attempt to make a description of 'display-buffer' more
amenable to both users and Elisp writers.  I would not be able to tell
beforehand whether a 'this-command' or 'category' entry in "app-action"
could affect whatever a user has specified in 'display-buffer-alist' and
how.

martin