It’s not an issue to be concerned about. It’s an appearance change I like, but it seems it’s a bit too advanced yet for some browsers. Next release I’ll probably remove it and instead just include it on my own site until browsers improve.
It concerns the positioning of the footer on various pages in relation to long and short contents. It is explained to some extent by the images included in this post here: http://kiwitrees.net/forums/topic/internet-explorer-scroll-bar-not-working/#post-6676