Nostalrius implemented a feature on their servers to block the AcceptTrade button in a Trade window for 2seconds after an item or money has been modified. This feature shall prevent scams.
(SOURCE) Twitter post announcing the feature
This AddOn is adjusting the visual for this feature, meaning once a change in the Tradewindow has been done the 'AcceptTrade' button will grey out for 2 seconds until Nostalrius allows you to accept the trade.
This should clear up any confusion while trying to accept a Trade.
- Download it from the repository here
- Unzip the archive and place the folder in your /World of Warcraft/Interface/AddOns/ directory
- If you download the code directly from GitHub you'll have to rename the folder from 'NostalriusAcceptTrade-master' to 'NostalriusAcceptTrade' after unzipping