bug#81512: [PATCH] Add command `outline-occur'

 > I have some questions or remarks about the new variable
 > `display-buffer-default-alist' you have added, about its semantics and
 > documentation.  I have not been following this thread, I apologize if I
 > miss something important.
 >
 > First, the name: this variable seems to be intended to override some
 > (default) behavior; it's binding has one of the highest priorities.
 > This means that it's on the other end than variables that are typically
 > named "-default", which are considered with lowest priority.  Unless I'm
 > missing something, the name is confusing and not consistent with our
 > typical nomenclature.

Agreed.  But we already have 'display-buffer-base-action' which probably
should have been called 'display-buffer-default-action' and the first
occurrence of "alist" is in 'display-buffer-alist' so it's reasonable to
have 'display-buffer-default-alist' right beneath that.  Anyway, feel
free to suggest a better term.  We'll be all ears I suppose.

 > Second: the added documentation says that this is a variable "which Lisp
 > programs may let-bind to specify conditional actions for nested
 > `display-buffer' calls."  I don't understand the connection to nested
 > calls here.  When at all is `display-buffer' been called recursively?
 > And in such a case, which variable is then crucial for which call of
 > `display-buffer'?  Is the outer or inner call ignoring one the variables?

A let-binding of `display-buffer-default-alist' is supposed to override
the ACTION argument of a 'display-buffer' call nested within that
binding.  For nested let-bindings of 'display-buffer-default-alist' the
usual rules for let-bindings apply.  If something is not clear about
this, we'll have to fix it.

 > Finally, it is not so nice to see how many variables we now have to
 > control or override the behavior of `display-buffer'.  I wonder whether
 > the design we have is really a good one, or if we have redundant
 > variables now.

Maybe.  Unfortunately, we also have to carry around obsolete variables from
bygone versions.

martin