title: OpenCV Return value from mouse callback function
body: <p>In OpenCV I want to return the point position like Point(x,y) to the main() function that I　click on the image in the mouse callback function . Is there anyway other than setting a global variable?</p>
  
  <p>I don't want to write all the codes inside the on_mouse() function.</p>
  
  <p>Thanks</p>