Re: Was it once possible to expand capped print output by using ellipsis as button?

[Stefan Monnier]

> I have vivid memory of being able to interact with those ellipsis as
> buttons, which would then expand and reveal previously invisible forms.

I think your memory is right.  The NEWS file for Emacs-21 says:

   *** The commands to evaluate Lisp expressions, such as C-M-x in Lisp
   modes, C-j in Lisp Interaction mode, and M-:, now bind the variables
   print-level, print-length, and debug-on-error based on the new
   customizable variables eval-expression-print-level,
   eval-expression-print-length, and eval-expression-debug-on-error.
   
   The default values for the first two of these variables are 12 and 4
   respectively, which means that `eval-expression' now prints at most
   the first 12 members of a list and at most 4 nesting levels deep (if
   the list is longer or deeper than that, an ellipsis `...'  is
   printed).
   
   <RET> or <mouse-2> on the printed text toggles between an abbreviated
   printed representation and an unabbreviated one.

> If this was in fact a feature, that was pulled out of stock emacs 
> I would find it very interesting to learn about the reason that forced
> such decision. 

I don't think it's been removed.  I've never used it, tho, so maybe it
doesn't work any more.  If so, try M-x report-emacs-bug.


        Stefan