python UI freezing

Question

I'm trying to make basic functionality after pressing "start" button start counter , after pressing stop button stop counter, but after I start process, it looks like only counting thread is working and it's not possible to press stop button

#!/usr/bin/python
# -*- coding: utf-8 -*-

import sys
from PyQt4 import QtGui, QtCore
from test.test_sax import start
import time
from threading import Thread
import threading
class Example(QtGui.QWidget):
    x = 1
    bol = True
    def __init__(self):
        super(Example, self).__init__()


        self.qbtn = QtGui.QPushButton('Quit', self)

        self.qbtn.resize(self.qbtn.sizeHint())
        self.qbtn.move(50, 50)
        self.qbtn2 = QtGui.QPushButton('Start', self)

        self.qbtn2.resize(self.qbtn2.sizeHint())
        self.qbtn2.move(150, 50)

        self.qbtn.clicked.connect(self.stopCounter)
        self.qbtn2.clicked.connect(self.startUI)

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Quit button')
        self.show()
    def stopCounter(self):
        Example.bol = False

    def startUI(self):
        Example.bol = True
        thread = Thread(self.counterr())

    def counterr(self):
        x = 0
        while Example.bol:
            print x
            x += 1



if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    a = Example()
    sys.exit(app.exec_())

thx

Answer 1

Now you call the slow function before you even create the thread. Try this instead:

thread = Thread(target=self.counterr)
thread.start()

In a Qt application you might also consider the QThread class that can run its own event loop and communicate with your main thread using signals and slots.