I've found this a while ago, and consider this a major bug but I haven't seen anyone posting it. I suppose this had happened quite a few time before I finally realized it is a bug, and I found it hard to resist the temptation to use it cause in the high difficult levels the trading terms are so ridiculous that I sometime felt like it won't be a fair deal unless I could sell my stuff twice.. and guess what, now you can
Anyway, here's how it happens:
1. enter the diplma window
2. trade whatever you want
3. click "we accept your offer" or whatever to close the deal, then click "we have another proposal" or whatever ASAP
4. in the new list, you will find the stuff you've just given away are still there for you to trade again
5. If you wait a few seconds before open the new window in 3 or you close the diploma window in 4 and open it again, things will be the way they should be--- those items are gone
Anyway, here's how it happens:
1. enter the diplma window
2. trade whatever you want
3. click "we accept your offer" or whatever to close the deal, then click "we have another proposal" or whatever ASAP
4. in the new list, you will find the stuff you've just given away are still there for you to trade again
5. If you wait a few seconds before open the new window in 3 or you close the diploma window in 4 and open it again, things will be the way they should be--- those items are gone
