The search works fine. However, I find that a non-match is misleading.
If for example you search for "abd" in a text containing "xxxxabcxxx",
"a" will be first highlighted, then "ab", then nothing (which is
not distinct from the default non-search mode). "ab" should be
highlighted in another color (red?) if possible, and no character should
be added to the search string when there are no matches.