Hi.

Attached is a small feature patch. Currently when a hi-lock.el function
is called interactively, the default offered by (read-regexp) is the
last value.

With the patch, the behavior is the same if no active region is
available; if an active region IS available, the default is the contents
of the region.

Perhaps something like this should be added to (read-regexp), but that's
a bigger proposal than this small patch.