The Shulchan Aruch (i will try to find the exact place) says that on a shabbos thats also tisha b'av you should mour n for the bais hamikdash b'tzinah (privately) verbally not saying good shabbos/shabbat shalom is not exactly private and he was doing it because the day was tisha b'av. Although he might have a special minhag (custom) to not say good shabbos/shabbat shalom, you might want to ask your friend about that.

Do we say "shabbat shalom" on Tisha b'Av that falls on Shabbat?
I'm attempting to put a frame around my section headings.  I am using the package mdframed which adds functionality to the framed package.  It basically draws a box around an object, in an environment.  So I wonder how I can do this.  Can I use \renewcommand, for example?  I'd really like to use mdframed to create the frame.
