I see that unicode characters can be found using the \uFFFF format (was \x{FFFF} coming from Sigil's PCRE), and at least some of the unicode categories work (I can find any letter in any language using \p{L} or \p{Letter}), but many of those unicode categories don't seem to have the granularity I'm accustomed to.
The bulk of the punctuation searches seems to work:
\p{P} all punctuation
\p{Pd} dashes
\p{Pi} opening quotes
\p{Pf} closing quotes
etc...
But \p{Ll} and \p{Lu} (or \p{Lowercase_Letter}, \p{Uppercase_Letter}) both seem to find all letters regardless of case--just like \p{L}.
Is this expected/known behavior?
EDIT: Ooops! Never really expected those classes to be subject to the case-sensitive check-box. My bad. Nothing to see here!