Underline spelling errors fails when a Doxygen comment like this is used:
enum Foo { Foo1 /**< The firrst. */ };
Above, "firrst" will not be underlined, although obviously typo-ed.
Changing the comment style to "//" or "/** ... */ or "/* ... */ makes the underlining work again, si I guess it's the '<' in "/**<" that makes your parser choke: