(4.) “Treat the following characters as alphanumeric” option applys only when editing. For instance, when you double-click a word, these characters are treated as a part of the word. However, this setting does not apply to the regular expression w operator nor the Search Only Word option in the Find dialog box. I will clarify the Help description.
(5.) I will add a description the lookbehind patterns must be of fixed length .
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