You can sort of customise this by watching or ignoring a category.
For example, I am ignoring the Testing Ground category here.
Would it make more sense to have all categories unwatched by default, as opposed to watched?
I actually saw the "Ignore" icon before, but didn't realize what it did. I thought it was something about ignoring users -- so I ignored it
Here you go!
This should get you started. You'll need to edit the composer.tpl, or inject html at composer load, checking if the post is a new topic.