Code review comment for lp:~jochym/phatch/pep8

Hmmm... I think the background color should never show through the
pictures. If I want to make a grid with transparent pictures, I like
them to remain transparent as they are without adding any color. It
should only be used for the border color (color in between images), eg
when you scale to the original image and you select 4x2 grid. So the
background color should be shown conditionally if n!=m.