From: <stsci.edu at jmadams> (John M. Adams)
   
   In acl-5.0.1, when expanding macros vi M-M, the eli displays the
   expansion in the minibuffer if it is small enough.  This is
   problematic if one wants to, say, expand twice.  Is there a way to
   always put the macro expansion in its own buffer?  I'm not usually
   interested in the terminal expansion given by M-W.
   
See the documentation on the elisp variable
fi:pop-up-temp-window-behavior which allows you to control general
pop-up info behavior.  This variable is global, so it affect all such
commands.

It would be possible to define your own version of fi:lisp-macroexpand
that behaves differently from the global setting, but it can't be done
the obvious way by simply binding the variable around the command
because the popup text is displayed by a continuation that runs
asynchronously from the command invocation.  In fi-lep.el see
fi::lisp-macroexpand-common.  elisp isn't a lexical lisp, so capturing
variables in continuations is more tedious than in a properly scoped
lisp.