Problems with hyphen in spell checking
Some types of hyphen are treated different in spell checking:
hyphen-minus (U+002D) works as expected (e.g. "one-half" is ok).
hyphen (U+2010) is shown as spelling error.
non-breaking-hyphen (U+2011) again is ok.
soft-hyphen (U+00AD) entity input is automatically converted, i.e. it is no longer visible, e.g. "ar­tistic" becomes "artistic", appears correct, but is shown as an spelling error.
The combination hyphen-minus + soft-hyphen (does not make much sense, but appeared in text pasted from a PDF) is also shown as an error. However, on right-click, the context menu items for spell checking are not shown.
hyphen-minus, hyphen and non-breaking hyphen should be treated consistently. The inconsistent handling of hyphen is a problem, since for good typography hyphen should be used instead og hyphen-minus.
soft-hyphen should be ignored by the spell-checker.
A way to make soft-hyphens visible would be useful. If there is, I did not find it.
Environment: Calibre 2.77 with Ubuntu 12.04 on 64-bit system.