How to link items from trade chat?

Is there a way to link items from a trade chat? For example I want to buy a weapon, so how to link this weapon to seller and ask him for price? I know ctrl + alt + left click to link items, but this work only for items in my inventory.

Exactly what I want to do and I am looking for help here :).

Thanks in advance and sorry for bumping such an old thread, but the guy there asked exactly my question.