ref: 2bd8e241a93165a99f5e2c4a2dd9c3b3b1e3c6f3
parent: c8c576f68949ecab29c8250222983c2b9d2931f7
author: Simon Tatham <anakin@pobox.com>
date: Tue Aug 9 13:14:25 EDT 2005
Implement error checking in Slant. Clue points are now highlighted in red if it's impossible to fulfill them (either through too many neighbours connecting to them, or too many not connecting to them), and edges are highlighted in red if they form part of a loop. In order to do this I've had to revamp the redraw function considerably. Each square is now drawn including its top and left grid edges, but _not_ its bottom or right ones - which means that I need to draw an extra strip of empty squares outside the actual grid in order to draw the few pixels which appear on the grid bottom and right borders and also to red-highlight border clues. [originally from svn r6174]