title: How to set a window icon with PyQt5?
body: <pre><code>from PyQt5 import QtWidgets, QtGui
  from PyQt5.QtWidgets import *
  from PyQt5.QtCore import *
  
  class Application(QMainWindow):
      def __init__(self):
          super(Application, self).__init__()
          self.setWindowIcon(QtGui.QIcon('icon.png'))
  </code></pre>
  
  <p>I am trying to set a window icon (top left of the window) but the normal icon disappeared instead.</p>
  
  <p>I tried with many icon resolutions (8x8, 16x16, 32x32, 64x64) and extensions (.png and .ico). </p>
  
  <p>What am I doing wrong?</p>