title: How to add items to a QComboBox in PyQt/PySide
body: <p>I need some help adding some items to a <code>QComboBox</code>. So I have two comboboxes, and one populates the other depending on the item selected.</p>
  
  <p>My question is that, using <code>additem</code> for new items, it works, but if I choose another option for the combobox, it adds the new items, but the previous items are gone - and there are blank items below the new ones.</p>
  
  <p>I thought that each time I chose a new option from the first combobox to clear the contents of the second combobox. So I used the <code>clear()</code> on the second - but it didn't work.</p>
  
  <p>That's how I thought of it :</p>
  
  <pre><code>self.comboBox_2.clear()
  for index,i in enumerate(list1):
    self.comboBox_2.addItem(_fromUtf8(""))
    self.comboBox_2.setItemText(index+2, QApplication.translate("Dialog", i, None, QApplication.UnicodeUTF8))
  </code></pre>
  
  <p>The above is part of a function that executes when the first <code>combobox</code> changes.</p>