FAQ 47 says that "On each comment page there is a small toolbar set in blue that offers a variety of buttons, one of which is a small red heart with a plus sign in the upper left corner" which is not true now that S2 and styled comment pages are here.
For example, Component seems to use a red heard without a plus sign (and the background behind the toolbar is not necessarily blue); The Boxer's heart is dark grey (at least, in the journal I'm looking at); custom styles may use something even more exotic.
Edit: A Sturdy Gesture appears to lack a way to add an entry to memories (see, for example, http://www.livejournal.com/users/avadriel/11637.html).