Merge notifications of two incoming messages from the same person

Quassel uses KDE's standard notification system.

I reckon this should be moved upstream actually. Perhaps Aurelien has some input as to which component actually needs changing here. AFAIK the knotification API does not really support persistence as it would be required to conduct merging, as the api predates the FDO thing.

The FDO spec does not explicitly support merging. What happens is notify-osd remembers the last notification and merges the new one in it if it satisfies a set of rules mentioned here: https://wiki.ubuntu.com/NotifyOSD#Merging_notifications

One of those rules is that the application must set a particular hint in the notification. Quoting notify-osd page:
"""
If the hint “x-canonical-append” is supplied with a string value “allowed”, and replaces_id is not specified, the bubble should be treated as if it allows merging.
"""

KNotification API does not let the application pass custom hints, so it is impossible for any application using this API to support merging notifications. It could be possible to fix this by doing one of those:

1. Remove the need for the "x-canonical-append" hint in notify-osd.

2. Modify knotify (the daemon handling notifications behind KNotification) to always pass the "x-canonical-append" hint.

3. Extend KNotification and knotify to allow applications to pass arbitrary hints *and* patch applications to pass the "x-canonical-append" hint.

Of those three, 1. seems doable, 2 and 3 are unlikely to happen.

Status changed to 'Confirmed' because the bug affects multiple users.