Proposed fix for issue #2623

This applies a new filter for adding a text below the first preview image in the gallery.

Use with a filter like this:
/* Add gallery click note */
add_filter('shopp_gallery_description', 'print_gallery_description');
function print_gallery_description ( ) {
	return '<style type="text/css">#shopp .gallery .previews li.fill{height: 260px;}</style>Click To Enlarge&#x2191;';
}