Add some comments

corfu-mouse.el

@@ -66,6 +66,8 @@
                     (corfu-complete)))
     (define-key map [mouse-1] mouse-1)
     (define-key map [mouse-3] mouse-3)
+
+    ;; Ignore these events to keep completion session alive.
     (define-key map [down-mouse-1] #'ignore)
     (define-key map [down-mouse-3] #'ignore)
     map))
@@ -78,6 +80,9 @@ FCANDS is the return value of `corfu--format-candidates'."
         (cands (caddr fcands)))
     (while cands
       (let ((line (car cands)))
+
+        ;; Append necessary amount of spaces to make it as wide as the
+        ;; popup.
         (setq line (concat line (make-string (- (cadr fcands)
                                                 (string-width line))
                                              ? )))