Thanks guys!

I found the library, though, as a .tar.gz file under /home/jeff/.cabal/packages/hackage.haskell.org/grapefruit-ui/0.1.0.5, and when I uncompressed that, found the UIItem file.

I can't find the offending character in it, though. Supposedly it was at position 12.2 (line 12, column 2, right?), but I only see whitespace there. The first few lines of it are these ("module" being the first word of the first line):

module Internal.UIItem (

    -- * User interface items in general
    UIItem (UIItem),
    item,

    -- * Bricks
    Brick,
    brick,
    just,

    -- * Boxes
    Box,
    box,
    with,
    With (With),