title: PyQt QComboBox setting number of visible items in dropdown
body: <p>I'm working on an application in PyQt that takes an object dictionary and allows you to plot the variables streaming from a robot in real time.  One of the things I'm working on to enable this is a drop down menu.  Unfortunately, we have a couple hundred variables, so my PyQt Combobox pops up from the top of the screen to the bottom with items when clicked.  I'd like to limit the number of items displayed at a time to 20, with the ability to scroll to see the rest.  I've tried using the documented setMaxVisibleItems method, but it doesn't affect the drop down at all.  Any recommendations?</p>
  
  <p>Code here:</p>
  
  <pre><code>#!/usr/bin/env python
  
  from PyQt4.QtCore import Qt
  from PyQt4.QtGui import QComboBox, QApplication
  
  from cli.parc2_od import cli_od
  import sys
  
  app = QApplication(sys.argv)
  
  items = cli_od.OD.keys() #Items to populate dropdown.
  combo = QComboBox()
  
  #The solution:
  combo.setStyleSheet("QComboBox { combobox-popup: 0; }")
  combo.setMaxVisibleItems(10)
  
  
  
  
  combo.addItems(items)
  
  combo.resize(300, 30)
  combo.show()
  
  
  sys.exit(app.exec_())
  </code></pre>