After seeing the "Invisible keywords" bug (2211412), I grep'ed for "white" and "black" in the .jsf files. mail.jsf has several uses, but they don't cause a problem because they set both the foreground and background. However, diff.jsf and spec.jsf use "dim white", and sml.jsf uses "bold black", without setting the background. Both "dim white" and "bold black" are visible on white and black backgrounds, respectively, but just barely. Try highlighting the attached files with the (un)appropriate background.
I think replacing the "dim white"s with "bold" should work fine. I'm not sure about the "bold black" in sml.jsf, since it already uses "bold" for keywords.