Allegedly adds the title="blah" to the subject link. Not sure, since my

browser doesn't actually pop up anything.  May or may not work.

Someone test it.  If it doesn't urldecode the subject (like if you see
pluses instead of spaces and %## a lot), let me know and I'll whip up
something else.  If you feel courageous, try changing it yourself.  Don't
forget to attempt to view subjects like this:
   #This"is a $nasty subject ! line that ' may or | may > not work

:-)

functions/mailbox_display.php

@@ -123,7 +123,8 @@
                    if (! isset($search_stuff)) { $search_stuff = ''; }
                echo "<a href=\"read_body.php?mailbox=$urlMailbox&passed_id=".$msg["ID"]."&startMessage=$startMessage&show_more=0$search_stuff\"";
                do_hook("subject_link");
-               echo ">$flag$subject$flag_end</a>$bold_end</td>\n";
+               echo " title=\"" . urlencode($msg['SUBJECT']) . 
+	          "\">$flag$subject$flag_end</a>$bold_end</td>\n";
                break;
             case 5: # flags
                $stuff = false;