Yes, the equity is updated only when trades are open.
I admit that this behavior may be confusing, so we'll change that in the next version. The displayed equity value will then be permanently updated.
It looks like this has been fixed in 1.10beta, too. Thanks. Much more sane now, looking at two Zorro windows and seeing the same numbers.
You might want to update the documentation, though. I've seen somewhere that the displayed value is "account balance", but it should be "account equity" instead.