ref: ea9142fbda5beec1e76c1ba8d3ee649be6946d03
parent: 2c85fd3530f3744fa270b7189fd82f4de460f2f3
author: Simon Tatham <anakin@pobox.com>
date: Mon Aug 29 05:05:35 EDT 2005
Ahem. The region density at which things start to get hairy is 2/3 of the grid area, not 3/2! [originally from svn r6235]