Об этом дополнении
Oddly an existing en-US spell-checker is shown as add-on instead of a dictionary, while the new en-GB 1.19.3 dictionary got this right. To fix this for en-US I copied Kevin's Hunspell archive, added the working en-GB 1.19.3 add-on magic, and submitted the result. Kevin's unmodified README_en_US.txt contains the copyright legalese.