I really like Doit.im's interface, but there's a major flaw in the way they handle the Next Actions list. Every project task appears as an actionable item by default (which is obviously ridiculous):

There's already a support thread where this is being discussed, but my inexperience with GTD makes me hesitant about my own suggestions, and there aren't enough others throwing around ideas (probably because it's a forum specific to Doit.im).
So I wondered if the folks here at PP.SE might have some insights.
Do other GTD software handle Next Actions lists effectively, and if so, how? I would go and try them all, but not only would I not be able to immerse myself sufficiently in each, but also I'm still learning GTD myself.
What's a clean way to distinguish Sequential vs. Parallel (Concurrent) tasks in a project?
(Please ignore the contents of my screenshot—I'm sure I'm doing it all wrong, but it's all for practice as I read the book concurrently.)