1 files changed, 5 insertions, 0 deletions
diff --git a/devel.but b/devel.but
index e481ec6..ea23d52 100644
--- a/devel.but
+++ b/devel.but
@@ -2671,6 +2671,11 @@ Calling this function is very likely to result in calls back to the
 front end's drawing API and/or \cw{activate_timer()}
 (\k{frontend-activate-timer}).
 
+The return value from \cw{midend_process_key()} is non-zero, unless
+the effect of the keypress was to request termination of the
+program. A front end should shut down the puzzle in response to a
+zero return.
+
 \H{midend-colours} \cw{midend_colours()}
 
 \c float *midend_colours(midend *me, int *ncolours);