Re: Shadowbox and Mootools in Tikiwiki 1.9.11
I imagine the wiki parsing code (maybe in lib/tikilib.php?) has been modified in 1.10 to give functionality to the "rel=shadowbox" syntax. If this is isn't easy to figure out by comparing the two versions' wiki parsing code, you could consider upgrading to 1.10 beta. It's actually pretty solid, though of course always a little risky as it's not as tested, etc.
-- Gary