Display price amounts with correct currency consistently

A site may accept payment in multiple currencies and CiviCRM records this fact in, eg. the currency field of a contribution.

However, on the various displays across the site it inconsistently displays prices using either the actual contribution currency or it defaults to the site currency — making it impossible to tell the currency used and how much was paid.

See for example the attached screenshot which is from /civicrm/contact/view/participant?reset=1&action=update&id=xxx — but this is just an example.