There is a temporary workaround available if you need to listen to Add or remove word actions perfromed by end users.
window.WEBSPELLCHECKER_CONFIG = { autoSearch: true, ...., onLoad: function(instance) { instance.subscribe('addWordToUserDictionary', function(data) { // Get the added `word` from `data.word` field }); instance.subscribe('deleteWordFromUserDictionary', function(data) { // Get the deleted `word` from `data.word` field }); } };