The rows were memoized, but nothing they were given kept its identity: the
list built each row's thread messages afresh, passed inline handlers and the
whole selection, and the click and context-menu handlers changed with the
selection and the menu. Every visible row rendered on every store write.
Rows now select their own message and conversation from the store, take a
plain selected flag, and get handlers whose identity never changes. The
conversation summary is memoized.
Refreshes also keep the object for a message whose fetched properties did
not change, so a refresh that changed one message renders one row.
jcoffey-dev
c6dbcaef63