True. I thought about that and concluded that it would be a lot harder
to look for more than one words, matching a certain expansion. It will
be especially tricky, I think, if the words the user types and which
match an extension, spans more than one line. Of course not impossible but
I thought I would start with the easy and probably quite common use
case.

Okay, so... Turns out it was not that hard... :)

With two helper functions I could rewrite the suggest function quite nicely:

(defun asug-count-words (expansion)

(length (split-string expansion " " t)))

(defun asug-get-previous-words (n)

(let ((end (point))

words)

(save-excursion

(backward-word n)

(replace-regexp-in-string

"[\n\r]" " "

(buffer-substring-no-properties (point) end)))))

(defun absug-maybe-suggest ()

"Suggest an abbrev to the user based on the word(s) before point."

(let ((expansions (absug-get-active-abbrev-expansions))

words found expansion word-count)

(while (and expansions

(not found))

(setq expansion (pop expansions))

(when expansion

(setq word-count (asug-count-words (car expansion))

words (asug-get-previous-words word-count))

(when (and (> word-count 0)

(string= words (car expansion)))

(setq found t)

(message "You can write `%s' using the abbrev `%s'."

(car expansion) (cdr expansion)))))))

It works for abbrevs that has an expansion with multiple words and

it also works across lines.

Now I will clean this up a bit and checkdoc it...