Yes, this was overlooked. Sorry about that. A couple of questions.
Is modifying an existing order supported by the exchange? The exchanges I've dealt with treat a modification as a cancel and resubmit (probably to get their cancel fees). I'm not sure if I'm put in the back of the line, thought. Also, I've looked at a couple of broker APIs this morning and I didn't see any way of changing an existing order. This isn't to say that it's impossible. I suppose adding a method to modify the order in the broker plugin isn't too bad and those APIs that don't support modification can do a cancel and re-submit.
What do you think?
Any thoughts on having the ability to modify a working order. As things stand at the moment I think you need to cancel the order and then place a new one. There are a couple of drawbacks doing it this way. Firstly if the order has been partially filled then there is some extra work involved in getting the unfilled quantity in order to place the new order. Secondly, if you are trading a deep market you may be sitting in a queue waiting to get done, and by cancelling the order and placing a new one (say if you wanted to alter the quantity of the order) you lose your spot in the queue and go to the back of the line. I don't think it is anything that is urgent, but it would probably warrent doing sometime in the future.