Send typing notification events when user types in the compose box.
Listen for these events and display a notification.
Sending notifications: Notifications are throttled, so that start
notifications are sent every 10 seconds of active typing, and stop
notifications are sent 5 seconds after active typing stops or when the
compose box is closed.
Displaying notifications:
When a typing notification is received, if the current narrow is private
messages or is: pm-with and the user is not the sender,
"Othello is typing..." is displayed underneath the last message. This notification is
removed after 15 seconds. If another notification is received during this period, the
expiration is extended. When a stop notification is received the notification is removed.
Internally, a list of users currently typing is maintained for each
conversation (in a dict). When an event is received the list (for the appropriate
conversation) is updated and the notifications template is re-rendered
based on the narrow information. This template is also re-rendered when
the narrow changes.
Significantly modified by tabbott for clarity.
Fixes#150.
Arpith Siromoney