The documentation states:
If a line starts with a '*' (asterisk), the GUI will
filter out all search results which contain the
specified phrase as a whole word. If the line does not
start with an asterisk, the GUI will filter out all
results that contain the given substring in their filename.
However, the actual operation of the GUI (confirmed by
reading the code) is the exact opposite to this: If a
line does not start with an asterisk, the GUI filters
out search results containing the phrase as a whole word.
See filter.c line 145, version 0.6.4