I think that's what's happening, because when I toggle the border, there's a maybe one-pixel-wide line (dis)appearing at the very edge of the screen about half the height of the minimap. I think that's the lower left part of the border.
Which option do you mean? I can dis/en-able the border under "skins" and choose the type of skin. I have it enabled and skin set to "square".
I also noticed today that the text from the questtracker is up and left right (must have been the brewfest) from its normal position now being on top of the minimap.
Might it be, that these elements dont get scaled correctly with my widescreen ui and therefor the border is way of the screen?