title: SDL2 running inside a non-main thread
body: <p>Having some confusion over what counts as the "Main" thread in this situation.</p>
  
  <p>I have QT running in my first thread which is blocking. I want to run SDL2 in a secondary thread, with all calls and initilisation isolated to this thread.</p>
  
  <p>Will this allow SDL2 to run correctly and stable as the Documentation states it needs to be in the main thread? Also this question <a href="https://stackoverflow.com/questions/22320906/sdl2-two-windows-in-different-threads">SDL2 two windows in different threads</a> states you can't use certain SDL2 functions outside the "main" thread.</p>
  
  <p>In this case is the main thread, as far as SDL2 is concerned, the first thread containing QT, or the second thread SDL2 was initilised in?</p>