(defun region-active-p ()
"Return t if Transient Mark mode is enabled and the mark is active.
-This is NOT the best function to use to test whether a command should
-operate on the region instead of the usual behavior -- for that,
-use `use-region-p'."
+To test whether a command should operate on the region instead of
+the usual behavior, use `use-region-p' instead. That returns nil
+for empty regions when `use-empty-active-region' is nil."
(and transient-mark-mode mark-active))
(defvar mark-ring nil