Great question! There are two things that need to be done here.
First, in qa_post_html_fields(...) in qa-app-format.php, insert these lines:
elseif (strlen($post['content']))
$fields['title']='<SPAN TITLE="'.qa_html($post['content']).'">'.$fields['title'].'</SPAN>';
... after ...
if ($microformats)
$fields['title']='<SPAN CLASS="entry-title">'.$fields['title'].'</SPAN>';
Second, you need to ensure that more full information about the posts is retrieved from the database wherever you show a question list. You can do this on an individual basis by making sure that the $full parameter is set to true whenever an appropriate function from qa-db-selects.php is called.
Or you can just take a shortcut and change qa_db_posts_basic_selectspec(...) in qa-db-selects.php - where it says:
if ($full) {
... you can replace with...
if (true) {
Please note that this will mean more information is being retrieved from the database, but it shouldn't make a meaningful speed difference.