Update: My overall goal here is to capture when users log out of the system, regardless of if they did it, or if they close out of their browsers.
Here is my potential solution:
Add a DeleteActionListener to the runtime when the app starts. (Mendix, can you please create a LogoutAction like your LoginAction???)
If the request is deleting an object of type System$Session, do something (like logging it).
To do this, you need to have PersistentSessions on. Thoughts or alternatives from anyone?