The user of-course can already implicitly work out this information from comparing the fee-rate with the actual fee.

I think that it would be useful for people not wanting to do this arithmetic in their head.

if (ExtractDestination(txout.scriptPubKey, address))
                    {
                        strHTML += "<b>" + tr("To") + ":</b> ";
                        if (wallet->mapAddressBook.count(address) && !wallet->mapAddressBook[address].name.empty())
                            strHTML += GUIUtil::HtmlEscape(wallet->mapAddressBook[address].name) + " ";
                        strHTML += GUIUtil::HtmlEscape(CBitcoinAddress(address).ToString());
                        if(toSelf == ISMINE_SPENDABLE)
                            strHTML += " (own address)";
                        else if(toSelf & ISMINE_WATCH_ONLY)
                            strHTML += " (watch-only)";
                        strHTML += "<br>";
                    }
                }
                strHTML += "<b>" + tr("Debit") + ":</b> " + BitcoinUnits::formatHtmlWithUnit(unit, -txout.nValue) + "<br>";
                if(toSelf)
                    strHTML += "<b>" + tr("Credit") + ":</b> " + BitcoinUnits::formatHtmlWithUnit(unit, txout.nValue) + "<br>";
            }
            if (fAllToMe)
            {
                
                CAmount nChange = wtx.GetChange();
                CAmount nValue = nCredit - nChange;
                strHTML += "<b>" + tr("Total debit") + ":</b> " + BitcoinUnits::formatHtmlWithUnit(unit, -nValue) + "<br>";
                strHTML += "<b>" + tr("Total credit") + ":</b> " + BitcoinUnits::formatHtmlWithUnit(unit, nValue) + "<br>";
            }
            CAmount nTxFee = nDebit - wtx.GetValueOut();
            if (nTxFee > 0)
                strHTML += "<b>" + tr("Transaction fee") + ":</b> " + BitcoinUnits::formatHtmlWithUnit(unit, -nTxFee) + "<br>";
        }
        else