Ever hear of WordPress app themes? They're somewhat new. These are no ordinary themes. Take for instance a dental office. You walk in and the dental assistant makes an appointment on the scheduling app. Only it's not an app per sé, but a WordPress theme that acts like a full-blown web application. The application may use some features of WordPress, but may not use others. Some of the files will load via an MVC framework kicked off by WordPress calling a theme's index.php file. Some of the files may use WP API calls, while other files may not use a single WP API call at all. Some app themes may simply use WordPress as the sales mechanism because things attached to WordPress have market uptake. (Note, almost all app themes are not available on wordpress.org.) Some app themes may simply use WordPress to borrow the same database, provide easy admin panels that people are used to using, and the rest might be something else entirely. Some may use pages and posts inside the app theme. It depends.<p>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?"<p>Here's what the FSF told Matt Mullenweg about it:<p>http://wordpress.org/news/2009/07/themes-are-gpl-too/<p>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?<p>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.