It seems that time and time again for each T5 project (6 out of 7 so far) I find I need to override tapesty.js methods to add additional support for zones. Currently there is only 1 event fired from a zone (Tapestry.ZONE_UPDATED_EVENT), I'd like to suggest/request there be at least 4 events total (3 new ones):
1) ZONE_BEFORE_AJAX_REQUEST_EVENT: This would be fired before the ajax request is sent to the server. Listeners should be able to cancel the ajax request (similiar to the way tapestry allows a form submission to be canceled)
2) ZONE_BEFORE_UPDATE_EVENT: This would be fired after the ajax request returns and just before the zone is updated via the processReply() method. Again, listeners should be able to cancel the update.
3) ZONE_UPDATED_EVENT: already and is listed here for completeness.
4) ZONE_AJAX_REQUEST_ERROR_EVENT: This would be fired if the ajax request errored out for the zone. (includes error data)
references to mailing list: http://tapestry.1045711.n5.nabble.com/More-javscript-zone-events-please-td4401005.html