Your listener id (must be unique)
Your listener function
// log a message in the console once a sub form dialog has been closed
JMap.Event.Form.on.subFormDialogClosed(
"custom-sub-form-dialog-closed",
params => console.info(`Form dialog closed for layer id="${params.layerId}"`)
)
JMap.Event.Form.on.subFormDialogClosed
This event is triggered each time a sub form dialog is opened.