Partial event payment status unclear in View Event Registration

The scenario is this: An event participant registers for an event and pays a deposit which is duly registered in CiviCRM. They then make subsequent partial payments.
Clicking View shows just the initial deposit payment, and nothing else.
Clicking the arrow on the left appears to show that the complete payment has been made, when the Fees part shows it has not.

I may be able to investigate, but some of you more knowledgeable in CiviCRM will probably arrive at an answer more rapidly.