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# -*- coding: utf-8 -*-import sysfrom PyQt4 import QtCore, QtGuifrom edytor import Ui_notepadclass StartQt4(QtGui.QMainWindow):	def __init__(self, parent=None):		QtGui.QWidget.__init__(self, parent)		self.ui = Ui_notepad()		self.ui.setupUi(self)				# Here we connect signals with our slots		QtCore.QObject.connect(self.ui.button_open, QtCore.SIGNAL("clicked()"), self.file_dialog)		QtCore.QObject.connect(self.ui.button_save, QtCore.SIGNAL("clicked()"), self.file_save)			def file_dialog(self):		fd = QtGui.QFileDialog(self)		self.filename = fd.getOpenFileName()		from os.path import isfile		if isfile(self.filename):			import codecs			text = codecs.open(self.filename, 'r', 'utf-8').read()			self.ui.editor_window.setPlainText(text)				def file_save(self):		from os.path import isfile		if isfile(self.filename):			import codecs			file = codecs.open(self.filename, 'w', 'utf-8')			file.write(unicode(self.ui.editor_window.toPlainText()))			file.close()		if __name__ == "__main__":	app = QtGui.QApplication(sys.argv)	myapp = StartQt4()	myapp.show()	sys.exit(app.exec_())Traceback (most recent call last):  File "start.py", line 21, in file_dialog    if isfile(self.filename):  File "/usr/lib/python2.5/posixpath.py", line 208, in isfile    st = os.stat(path)UnicodeDecodeError: 'ascii' codec can't decode byte 0xf3 in position 23: ordinal not in range(128)