KPassivePopup is hideous and broken in many ways. Currently it serves two purposes:
- As a fallback for when no other notification system is available. (Non-linux or when no notification daemon is running). For Windows (D21661) and macOS (D22365) we're about to get proper native notifcation support. The case where no notification daemon is running is IMHO an edge case that we don't need to support. Removing the fallback would allow to clean up the implementation and public API (for KF6) of KNotifications.
- Directly by applications. A guick grep over the KDE codebase found few users of it (KHTML, KDevelop, Lokalize and KTeaTime (D22542)).
Given it's brokeness and relative usefulness I propose to remove it. Since it's public API of KNotifications we obviously only can to it in KF6, so I propose to mark it as deprecated now and remove it in the KF6 transition.
Marking it as deprecated currently has a nasty side effect: Since it is still used internally (until we decide to drop the notification fallback) this results in deprecation warnings when building KNotifications. I'd be fine with not merging this patch for this reason, my main intention of this patch is to trigger a discussion about the future.