If one creates KNotification with CloseOnTimeout flag, the object itself gets deleted before the visual popup notification is hidden. The timeout for the hiding can be paused by hovering mouse over the popup, but this does not stop the KNotification destruction timeout. This results in non-working popup buttons after the timeout as the KNotification object gets deleted and thus the connection is invalid. Solution might be to also pause the KNotification destruction timeout. But as I don't understand the internals of this, I'm not sure this is possible. We're hitting the bug quite heavily with KDE Telepathy as users are clicking the buttons but nothing actually happens (the usual flow is like - user spots incoming message, moves the mouse to the button, reads the actual message (timeout is running), after he read the message, he clicks the button, which is invalid by that time). Tested with Plasma from 4.8 master.
Ping, any progress? This issue still present in 4.8 and it's quite annoying.
Since the Notification widget was replaced with a newer QML-based one, the previous versions are now considered unmaintained. There will be no more code contribution to the older versions. Please only report bugs and wishes to the new version, available since KDE 4.10