title: QComboBox click event
body: <p>I have been trying to get a <code>QComboBox</code> in PyQt5 to become populated from a database table. The problem is trying to find a method that recognizes a click event on it.</p>
  
  <p>In my GUI, my combo-box is initially empty, but upon clicking on it I wish for the click event to activate my method for communicating to the database and populating the drop-down list. It seems so far that there is no built-in event handler for a click-event for the combo-box. I am hoping that I am wrong on this. I hope someone will be able to tell me that there is a way to do this.</p>
  
  <p>The best article I could find on my use-case here is from this link referring to PyQt4 <code>QComboBox</code>:</p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/7021768/dropdown-event-callback-in-combo-box-in-pyqt4">dropdown event/callback in combo-box in pyqt4</a></li>
  </ul>
  
  <p>I also found another link that contains a nice image of a <code>QComboBox</code>.
  The first element seems to be a label followed by a list:</p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/21186779/catch-mouse-button-pressed-signal-from-qcombobox-popup-menu">Catch mouse button pressed signal from QComboBox popup menu</a></li>
  </ul>