Fix dismissing unread badge for thread message in desktop app - Add intersection-observer polyfill
- https://github.com/w3c/IntersectionObserver/tree/master/polyfill
- supports thread messages scrolling and marking messages read in old browsers
- mainly meant to temporarily support the OSX desktop app
Closes #2348 (closed)
Testing strategy
It's not trivial to build the old version of the desktop app. An easier option is to pick a browser that doesn't support IntersectionObserver
API from https://caniuse.com/#search=intersectionobserver
I went with testing in IE11.
- Test that new thread messages are marked as read after being displayed in TMF
- Test that scrolling up in TMF fetches older messages (infinite scrolling)
Edited by Eric Eastwood