Function which calculates how much money is engaged by a total of all trades

I got a simple expert (This is the MovingAverage.mq4) provided by MT4, which can not loose more than 20% if the account. 

context : 

Balance is 10000 Euros / Currency Euro

pair EURUSD

Leverage 1:200

You need to write a new function which calculates how much money is engaged by a total of all trades (from a same expert ) and displays an alert

means, if the expert looses 2000 euros, the expert must stop immedialty

Important:

**** do not use those following functions as BalanceEquity or MarginFree, or MarginRequired or whatever.

Just, calculate the amount of money for each trade with OrderProfit(), OrderLots() , OrderOpenPrice() ..