2009/10/01 Purchase of commodity
  Assets:Brokerage                10 AAPL
  Assets:Checking                -100 EUR

2009/10/01 Purchase of commodity with second currency
  Assets:Brokerage                10 AAPL
  Assets:Checking                -100 CAD

2009/10/02 Purchase of commodity with third currency
  Assets:Brokerage                10 AAPL
  Assets:Checking                -100 ECD

2009/10/03 Exchange of one currency to another
  Assets:Checking                     $30
  Assets:Checking                  20 EUR

; Price entry for the other currencies

P 2009/10/04 00:00:00 CAD $1.60
P 2009/10/04 00:00:00 ECD $1.60

; Now, the person asks for a report using -X $.  We have enough information to
; report the value of 30 AAPL in terms of of its present dollar value.  But
; what would the Unrealized Gains transactions look like?