I also feel someday/maybe is a bit too generic in strict GTD, I prefer having an intermediate "later" place for things that should be done ASAP but I know I can't get to for a while. However I think GTD would say to put those back into someday/maybe so I understand the request.
I was wondering about this "future projects" tab. Is putting stuff there manually the only way to get things in there or do scheduled actions also go there? What about inactive with a later start date, are they not considered "future"?
As I'm going through the screens, panes and tabs, more and more I feel it's a bit scattered, disorganized and sometimes redundant. But this is getting off topic, I'll think about it a bit more and post some suggestions separately.