I don't think this is possible, unfortunately. This seems to be using a different mechanism instead of configuration changes.
- Setting up a service to listen for
android.intent.action.CONFIGURATION_CHANGED
does not receive an Intent when a new font is selected in the dialog (but it does when the font size is changed, for example).
- If it was handled as a configuration change, then the activities would be restarted, but not the app itself, as it's the case here.
- Even if it were, the
android:configChanges
attribute does not accept arbitrary values, but only those listed in the documentation. So there would be no way to handle custom configuration changes.
If I had to guess, I'd say that Samsung's custom UI forcibly restarts all applications whenever the font is changed.