As I know, it’s not possible.

The event registry and the corresponding actions run on top of the Oracle Server, and the evaluation and execution totally happens within the database. It has no OS control over individual client machines \ servers.

Only Custom Menus can be used to run an external application over a user interaction on the application.

However, this is achievable via a series of client modifications or customizations. But, I won’t recommend it as it isn’t worth it, and not reliable as well.

I was afraid to get such a response.
I have a custom event action which cannot nicely run, as I have to consider both error messages to display on the screen AND to run some editions…

We don’t have the authorizations to custom the client, so no worries about that.

We will see what we can do in such a context, and thanks anyway