When I put a pokemon in the "new trade" slot of the trading machine, and closed the window - my pokemon had vanished! I was expecting it to return to my party but it wasn't there. It wasn't in the machine either. I had a backup save, but this is a problem.
To sum up, if you close the trade window while you have a pokemon in the "new trade" slot, if you haven't put it up for trade it still vanishes.
To sum up, if you close the trade window while you have a pokemon in the "new trade" slot, if you haven't put it up for trade it still vanishes.