title: The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support
body: <p>I am trying to work with opencv on mac for facial identification, but keep getting this error message:</p>
  
  <pre><code>The function is not implemented. Rebuild the library with 
  Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian,
  install libgtk2.0-dev and pkg-config, then re-run cmake or configure
  script in function cvShowImage
  </code></pre>
  
  <p>I am using python on mac osx and installed opencv using pip. Does anyone have past experience with this error and if so, how did you fix it?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import numpy as np
  import cv2
  
  face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
  eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')
  
  img = cv2.imread('/william.jpg')
  gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  
  faces = face_cascade.detectMultiScale(gray, 1.3, 5)
  
  for (x, y, w, h) in faces:
      img = cv2.rectangle(img, (x, y), (x+w, y+h), (255, 0, 0), 2)
      roi_gray = gray[y:y+h, x:x+w]
      roi_color = img[y:y+h, x:x+w]
      eyes = eye_cascade.detectMultiScale(roi_gray)
      for (ex, ey, ew, eh) in eyes:
          cv2.rectangle(roi_color, (ex, ey), (ex+ew, ey+eh), (0, 255, 0), 2)
  
  cv2.imshow('img', img)
  cv2.waitKey(0)
  cv2.destroyAllWindows()
  </code></pre>