Emacs.app highlighting madness
After finally getting my keyboard set up as I like it and sitting down to code, I discovered a new feature of Emacs.app for OS X, kind of. Placing the cursor on an opening or closing delimiter (paren, brace) highlights the whole expression by default. Unfortunately the default color choice turns my screen unreadable every time I put the cursor on an opening brace of a long class definition, flashes the arguments of a function call every time I type it, and otherwise continually taunts me.
With the help of the emacs-app-dev- mailing list I discovered the the culprit is mic-paren.el, a lisp package that extends the usual paren matching package paren.el. (setq paren-sexp-mode nil) has restored peace to my screen.