gitk touching paths highlighting oddity

Hi,

Using gitk (1.6.0.4) within a given subdirectory of a working tree, I wanted to
see those commits that affected files in the current directory so I selected
touching paths" and then typed "." into the entry field (That's right isn't it?)

On pressing the Next button, not only was a relevant commit successfully found
and highlighted (commit message boldened) but all of the "." characters in the
commit message list were given a yellow background (as if I was 
searching the text for "."). Surely the yellow text highlighting shouldn't
happen when finding paths?

A quick look at the gitk code left me no wiser hence this email.

Mark