This is a very small addon which simply makes a screenshot each time you trade with someone. I created the addon as a log of all trades I have done and to be sure to have prove when people accuse me of scamming them or vice versa.

On default players in your friend list or guild will be ignored and no screenshot will be made of the trade window when trading them. You can change this setting at the Ace preferences panel.

When either you or the other player accepts the trade window it makes the screenshot. It can't do this when both accepted it since the trade window disappears before the screenshot is taken which may result in multiple screenshots at once when someone keeps changing the items, but this shouldn't happen a lot.

In about 1 month time I have made about 500 screenshots worth around 250MB at a 1600x1050 resolution. It takes about 1 to 2 seconds for each screenshot to be taken so you may find the second of waiting annoying but I really enjoy being able to look back at my trades. Remember lower resolutions will use less disk space (1023x768 will use about half the space mine does).

Known problem:
If both you and the player accept at the same time you may make two screenshots (this is an error with the WoW events). This will be very rare though.