Now that you know what a WordPress app theme is, the question is, "If a given PHP file doesn't make a single WP API call in it, but the parent file that called it may make a WP API call, does that file also mean it must be GPL as well because WP is GPL?"
Here's what the FSF told Matt Mullenweg about it:
http://wordpress.org/news/2009/07/themes-are-gpl-too/
However, did the FSF take into consideration my question above in the case of an app theme? That's a bit different, don't you think?
Here's my conundrum. I've put family life on hold, which hasn't been easy for me at all for me and my marriage. I've been drinking water and eating bread some days, almost. I did all this so that I could have the time to spend 30 days coding a WordPress app theme. Now that it's finished, I want to market it behind a paywall and get paid for my hard work. I want to ensure that when I told my wife, "We'll make some great sales here on this," that I was telling something realistic. But there's woothemes.com and cheapwoothemes.com as an example. Like that, I don't want someone to fork my stuff and sell it as their own accomplishment, perhaps doing nothing but changing branding, eroding all my seriously hard work.