According to https://bugzilla.xfce.org/page.cgi?id=quicksearch.html searching for 3 letter words should work, shouldn't it? E.g. searching 'svg' or 'png in product ristretto should list entries.
Searching for a word part does not work either. E.g. 'freeze' does not list bugs containing 'freezes'  (e.g. search ristretto for freeze vs. freezes).