old_contents: from _external import *
  
  if windows:
      gl = LibWithHeaderChecker('opengl32', ['windows.h','GL/gl.h'], 'c', name='gl')
  elif macos:
      gl = LibWithHeaderChecker('OpenGL', ['AGL/gl.h'], 'c', name='gl')
  else : # unix
      gl = LibWithHeaderChecker('GL', ['GL/gl.h'], 'c', name='gl')
  
  
  
new_contents: from _external import *
  
  if windows:
      gl = LibWithHeaderChecker('opengl32', ['windows.h','GL/gl.h'], 'c', name='gl')
  else : # unix
      gl = LibWithHeaderChecker('GL', ['GL/gl.h'], 'c', name='gl')
  
  
  
subject: use GL instead of AGL on osx