When using custom height of 50, this is what I get for <Navigator.NavigationBar style={{height: 50}}> (as you can see it's not vertically centered):

When using a negative marginTop to adjust both the back button and the title, it cuts off the top of the back button:

What's the proper way to fix this (preferably without negative margin)?
RN 0.30 / Mac OS X 10.11.5 / iPhone 6 / iOS 9.3
P.S: I could only find this other issue, but it's not too helpful: #3142