import sys
from PyQt4 import QtCore
from PyQt4 import QtGui 

class QuitButton(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Icon')

        quit = QtGui.QPushButton('Close', self)
        quit.setGeometry(10, 10, 60, 35)
        self.connect(quit, QtCore.SIGNAL('clicked()'),
            QtGui.qApp, QtCore.SLOT('quit()'))

app = QtGui.QApplication(sys.argv)
qb = QuitButton()
qb.show()
sys.exit(app.exec_())


quit = QtGui.QPushButton('Close', self)
quit.setGeometry(10, 10, 60, 35)

self.connect(quit, QtCore.SIGNAL('clicked()'),
QtGui.qApp, QtCore.SLOT('quit()'))

from PyQt4 import QtGui, QtCore