title: How to refresh items in Qcombobox [python]?
body: <p>I have a list of data which is shown in the Qcombobox (using 'addItems')
  Now - if the list is changed by loading data from a file with pushbutton - i don't see the new data in the combobx.
  The new data is there (I can print it after loading)
  What do I miss?
  below is the code for the simplified gui</p>
  
  <pre><code>from PyQt4 import QtCore, QtGui
  from PyQt4.QtGui import QFileDialog
  import pandas as pd
  
  try:
      _fromUtf8 = QtCore.QString.fromUtf8
  except AttributeError:
      def _fromUtf8(s):
          return s
  
  try:
      _encoding = QtGui.QApplication.UnicodeUTF8
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig, _encoding)
  except AttributeError:
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig)
  
  class Ui_MainWindow(object):
      def __init__(self):
          self.comboData=['None']
  
      def setupUi(self, MainWindow):
          MainWindow.setObjectName(_fromUtf8("MainWindow"))
          MainWindow.resize(456, 172)
          self.centralwidget = QtGui.QWidget(MainWindow)
          self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
  
          self.comboBox = QtGui.QComboBox(self.centralwidget)
          self.comboBox.setGeometry(QtCore.QRect(120, 60, 69, 22))
          self.comboBox.setObjectName(_fromUtf8("comboBox"))
          self.comboBox.setEditable(True)
          self.comboBox.addItems(self.comboData)
  
          self.pushButton = QtGui.QPushButton(self.centralwidget)
          self.pushButton.setGeometry(QtCore.QRect(260, 60, 75, 23))
          self.pushButton.setObjectName(_fromUtf8("pushButton"))
          self.pushButton.clicked.connect(self.load)
  
          MainWindow.setCentralWidget(self.centralwidget)
          self.menubar = QtGui.QMenuBar(MainWindow)
          self.menubar.setGeometry(QtCore.QRect(0, 0, 456, 21))
          self.menubar.setObjectName(_fromUtf8("menubar"))
          MainWindow.setMenuBar(self.menubar)
          self.statusbar = QtGui.QStatusBar(MainWindow)
          self.statusbar.setObjectName(_fromUtf8("statusbar"))
          MainWindow.setStatusBar(self.statusbar)
  
          self.retranslateUi(MainWindow)
          QtCore.QMetaObject.connectSlotsByName(MainWindow)
  
      def retranslateUi(self, MainWindow):
          MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
          self.pushButton.setText(_translate("MainWindow", "Load", None))
  
      def load(self):
          fileName=QFileDialog.getOpenFileName(MainWindow,'Load File')
          data_pd=pd.read_csv(fileName,index_col=0,na_filter=False)
          self.comboData=list(data_pd.var1)
          print(self.comboData)
  
  
  
  if __name__ == "__main__":
      import sys
      app = QtGui.QApplication(sys.argv)
      MainWindow = QtGui.QMainWindow()
      ui = Ui_MainWindow()
      ui.setupUi(MainWindow)
      MainWindow.show()
      sys.exit(app.exec_())
  </code></pre>