shoneill -
You are correct that the current behavior is for the icon to change back to the open folder even when you have been active on that thread. It might be possible for us to change that behavior so that once you have participated in a thread, the icon will remain the closed yellow folder with the blue arrow on it rather than reopen if there is new activity.
Alternate methods for keeping track of which threads you have participated in would be to check your subscription list either in your dashboard or in the Subscription tab in your profile. You could also float the threads to the top of the boards so that they stay on your radar. My third suggestion would be to click on "Find all posts by this user" from your profile page.
What are other people's opinions on whether the icons should be changed? Do you have other ideas for alternate methods to see what you have posted to?
Thanks,
Molly K.
Web Support & Operations Manager
National Instruments