[sweezyjeezy]

Not quite, it stacks neighbouring columns with the same pattern of colours on top of each other, e.g. http://i.imgur.com/35N4tPu.png

The columns have to be the same pattern exactly (same height, same colours)

[sharkdp]

Exactly! The code for stackEqual is here: https://github.com/sharkdp/cube-composer/blob/master/src/Tra...

I should definitely add a better description somewhere!