title: React Native Navigation Gesture
body: <p>I am using React Native's <code>Navigator</code> to navigate through scenes in iOS app. I found that although I can swipe back to previous screen by swiping from left edge to right, it looks like the region that I can swipe is not as big or responsive as the native navigation. Sometimes I swipe a little off the edge and it doesn't work.</p>
  
  <p>I am wondering if there is a way to apply some tuning to this area, i.e. make the swipe go back area a little bigger so user have better success rate.</p>