4.3 Margin Calls. In the event that, in the opinion of Hotspot FXr and in accordance with Hotspot FXr’s reasonable estimate of the then prevailing and obtainable market spot dealing rates, a Customer’s Account Balance should fall below the Margin Requirement for an individual Open Position or for a group of Open Positions or for the Customer’s Account in the aggregate, Hotspot FXr shall, at its discretion, have the right, but not the obligation, to liquidate any or all Open Positions in the Customer’s Account, and the Customer shall remain liable for any resulting deficit balances;
This is how it works with any margin account. If you are paying attention, sticking to stops, and only trading intraday, then you won't end up owing money. Even if you keep a losing trade and lose most of your equity, they just close out your position. The scenario where you could end up owing money is most likely with large overnight gaps in price - pure day trading eliminates this risk.
Sometimes with stocks and with commodity futures, they will halt trading when there is big news, good or bad. Then when they re-open it, there is an intraday gap in price that can be very big. With stocks, if you get stuck in a position when trading is halted, you're screwed. These situations are very rare, but they do happen, at least with stocks and cme futures.
Do they ever halt trading in Forex? What if there is giant news, like a terrorist event, nuke, or political assasination?