title: frozen window during heavy operation
body: <p>im trying to load some files from folders and i want to show the progress of it with progress bar. At this point i tried multiprocessing, timers, threads and nothing is working... I dont know why my code is not working.
  after run this code it shows me basic window but after line where i want to compare files, which is heavy operation, but im calling refresh of prograss bar here and in my console i see that it is working but the window with progress bar is frozen the whole time and never refresh :(( (Not responding)</p>
  
  <pre><code>#here is box with progress bar
  self.ex[0]=showLoadingBox(len(files[1]))
  #this is the heavy operation that i want to show the progress
  duplsCompare=self.comPictures(files, sett.qualityMeasure)
  #---------------------------------------------------------------------------
  def comPictures(self,ignSource, prepQ):
      dp = []
      ret = []
      source = ignSource[1]
  
      for index, item in enumerate(source):
          #here im trying to refresh progress bar
          reload(self.ex[0],index+1)
          for p in source[index + 1:]:
              #do some stuff with files...
  
      #return comparedFiles
  # --------------------------------------------------------------------------------------------reloading method
  def reload(self,load):
      if(not(self.count==0)):
          val=int((load/self.count)*100)
      else:
          val=100
  
      self.pBar.setValue(val)
      print(val)
  
      if(not(load&lt;self.count)):
          self.close()
  </code></pre>
  
  <p>After end of comparing the window start working but that worthless for me i need that prograss bar show the prograss of comparing.</p>
  
  <p>UPDATE:
  so i use threading module but still no progress here literally. Window with progress bar just frozen and show me no progress and not reponding still the same problem even with different thread...</p>
  
  <pre><code>    retComPic=[]
      t=Thread(target=self.comPictures,args=(files, sett.qualityMeasure,retComPic))
      t.daemon = True
      t.start()
  
      while(not(len(retComPic))):
          reload(self.ex[0])
  
      t.join()
      # self.ex[0].close()
      duplsCompare=retComPic[0]
  </code></pre>
  
  <p>The result is the same percentage right in the console but progress window frozen   </p>