Well, I hoped it was clear enough. Anyway, here is why I think it's unnecessary: The yellow colour stands out well on the gray background so you can already see which parts of the forum have new posts easily. On the other hand, if there are no new posts in the sub-forum the icon has a lower contrast (gray colour) which doesn't stand out anymore so you can just ignore it. Making forums with new posts have
![Darkness :darkness](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/darkness18x18.png)
as an icon and
![Death :death](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/death18x18.png)
for no new posts sounds like flexibility that is just not needed here. There is no need for it, and the practical use for it is really low. And while some people will like this, others won't, and there are other forum suggestions with higher priority than this suggestion here.
Long story short, see my last post
![Wink ;)](https://elementscommunity.org/forum/Smileys/solosmileys/wink.gif)