A friend of mine found a script that brings up OSX’s FileMerge program instead of the text-based file comparisons you get with mercurial with doing an “hg diff”.
- download this script and make sure its location is in your PATH
- add the following to .hg/hgrc:
[extensions] hgext.extdiff = [extdiff] cmd.opendiff = fmdiff
- Now type hg opendiff <filename> (hg op is enough), instead of hg diff <filename>