The Framework.TradeHistory collection is a Dictionary of all historic activity on the account: closed trades, cancelled pending orders, and also credit movements (provided that the back-end platform provides this data).
The history must be explicitly requested. It is empty by default.
To watch for the list being filled, and subsequently updated - you can use an OnMessage() handler.
If/once filled, the collection is a Dictionary of FXB.Order objects, keyed by their orderId properties. (As noted above, FXB.Order is used to represent a number of things, including all of trades, pending orders, and credit movements.)