The list of all the messages that are being loaded by this history event.
The discriminating type of this event.
OptionalupdateIndicates that modifications were made to the given messages and that updates to those messages should be saved in the history store. This is similar to the update behavior of the "pre:receive" event that is handled automatically.
The event is fired whenever the widget begins processing a list of messages that have been loaded from history. This event may be fired not only when the history is first loaded but it may be fired later during the life of the widget if additional messages are loaded from history.
This event is fired when this process begins. This is fired before all the "pre:receive" and "receive" events are fired which means that the messages here are the original messages before any possible modifications by the event handlers.