This addon will change the background color of threads on the thread list if a user has participated in a thread. The addon has usergroup permissions to control which groups can see this. It also has a user setting so users can turn it on or off in their preferences.
Admins can set the color in each of their styles via a style property.
Highlighted example:
Style property:
Usergroup permissions:
User option:
Admins can set the color in each of their styles via a style property.
Highlighted example:
Style property:
Usergroup permissions:
User option: