forgive me if i misunderstood your reply, english is not my first language 

the application has no access to funds or to exchange wallets or to your order book.
when you hit "Calculate" the server requests public market data from the exchange and with the data calculates profit/loss of your trade.
the app is just a calculator, not a orderbook manager or similar.

or you was proposing some kind of alarm when, for example, a trade loss is too big?
that would be a nice feature actually

btw, not sure when, but next version should integrate websockets for real time updates and you should be able to save a trade client side and maybe here i can put the feature you suggest