[emacs-wiki-discuss] Prompt for note on task completion?

[TC]

I vaguely remember, from my first use of planner, that there was
a way to have a remember buffer pop up when a task was being
completed.  I used it to optionally add some commentary about
the task I'd just completed. (I can't remember if the resulting
note got linked to the task.)

Am I imagining things, or does that feature exist?  I've twiddled
around among the lisp, to see if whatever C-c C-x does could
possible hook into a call to remember, but as far as I can make
out all that happens is an "X" gets marked on the completed task.

tc