re: xmas Walker sprite
I've emailed namida with a corrected copy of the Walker sprite - thanks for pointing this one out @Jeremy, I thought I'd already dealt with this but apparently not.
The copy I've emailed to namida also corrects the skin colour (a few of the pixels were incorrect).
EDIT: I've now thoroughly checked all default and xmas hi-res sprites for things like stray pixels, missing colours, incorrect shading, etc. I've PMd them to namida and, pending discussion of the changes, they should be ready in time for a future update.