v5.10.0 | WebSpellChecker

Implemented support of right-to-left (RTL) mode for a new floating proofread dialog. Thus, user interface elements for such RTL languages as Arabic or Hebrew will be mirrored compared to the left-to-right languages.
Updated localization of the WProofreader user interface, specifically suggestion pop-up and floating dialog, for English (en), French (fr), Arabic (ar), Hebrew (he), Ukrainian (uk) and Italian (it). Also created localization for Russian (ru).
Added a new onToggle callback that allows listening to the application state changes from enabled to disabled.

Implemented support of a user-level dictionary for the AI-based engine. Now users can add words to their dictionaries using the Add word button for spelling type problems. Those words won’t be underlined until this word in the dictionary.
Added support of the Russian dictionary with strict Cyrillic ‘Yo’ / Unicode ‘Io’ as a separate language option with the language code: ry_RU, (source: https://extensions.libreoffice.org/en/extensions/show/russian-dictionary-pack). Available on demand.
Updated 3rd party engine, LanguageTool, to version 5.2. Added and improved grammar rules for the next languages: Catalan, Dutch, English, French, German, Portuguese, Russian, Spanish and Ukrainian.

[WP-3737] WProofreader: Replace action doesn’t work in the unfocused state of inline CKEditor 4
[WP-3747] WProofreader: Overwritten style of font from normal to bold and no line break in dialog
[WP-3723, GitHub#18]: WProofreader plugin for CKE5: If backend is unavailable for more than 5 requests, the instances states won’t be synchronized