title: QLineEdit.setText only works once in function
body: <p>I'm currently trying to program for my bachelor thesis. The main part works, so now I want to implement a user interface. I watched some tutorials and worked via trial and error, and my user interface also works. So far so good. But yesterday I changed a small thing and that doesn't do what i want. I have a button saying "start program", and a line-edit where i want to display the current status. My code is:</p>
  
  <pre><code>import sys
  from PyQt4 import QtGui
  from theguifile import Ui_MainWindow
  import otherfile
  
  class Main(QtGui.QMainWindow):
  
      def __init__(self):
          QtGui.QMainWindow.__init__(self)
          self.ui=Ui_MainWindow()
          self.ui.setupUi(self)
          self.ui.mybutton.clicked.connect(self.runprogram)
  
     def runprogram(self):
          self.ui.mylineedit.setText('Running') # doesnt work
          try:
              otherfile.therealfunction() # works
          except ErrorIwanttocatch:
              self.ui.mylineedit.setText('thisErrorhappened') # works
          else:
              self.ui.mylineedit.setText('Success') # works
  
  app = QtGui.QApplication(sys.argv)
  window = Main()
  sys.exit(app.exec_())
  </code></pre>
  
  <p>Everything works as I want except from <code>lineedit.setText('Running')</code>. What I want is that "Running" is displayed while <code>otherfile.therealfunction</code> is working. I guess I have to update the line-edit somehow? But until now I didn't figure out how I can do that. I also set the line-edit readonly because I don't want the user to be able to change it, so maybe that's a problem? I thought readonly would only affect what the user can do.</p>
  
  <p>I am using Python3 and PyQt4 with Qt Designer.</p>