Hello Jean-Marc,
I have exact the same problem.
I have an Idle-url which requests a CiscoIPPhoneText with onAppFocusLost and onAppClosed set.
onAppFocusLost is working as expected, but onAppClosed does not.
In the documentation is mentioned, that onAppClosed is only supported in use with the Notify-event, so we have the following url:
onAppClosed="Notify:http:192.168.0.33:80:event.xml?event=closed"
When I look in the log of the phone requesting the Idle-url, I found the following warning:
WRN 13:50:19.780292 JVM: Startup Module Loader|cip.push.z:? - PushThread::execute--(Macro

Notify:http:192.168.0.30:82:event.xml?event=closed::<notifyApplicationEvent appId="jdm/PeterConnects" type="closed"/>)not allowed in execute objects),WILL NOT EXECUTE
This is probably the reason why the closed event is not executed, but how can I make this event being fired?
I tested this with a 7942/SCCP42.8-4-2S
Kind Regards,
Frank Jong