See this release note: https://addons.mozilla.org/ru/firefox/addon/epubreader/versions/?page=1#version-1.5.0.11 https://addons.mozilla.org/ru/firefox/addon/epub

See this release note: https://addons.mozilla.org/ru/firefox/addon/epubreader/versions/?page=1#version-1.5.0.11 https://addons.mozilla.org/ru/firefox/addon/epubreader/versi... Your mother is likely to weather the transition to WebExtensions well enough.