PyQt - QPushButton

import sys
from PyQt4 import QtGui, QtCore

app = QtGui.QApplication(sys.argv)
widget = QtGui.QWidget()

widget.setGeometry(200, 100, 400, 300)
widget.setWindowTitle('PyQt Application')

close = QtGui.QPushButton(QtGui.QIcon('lucia.png'), 'Close', widget)
close.setGeometry(10, 10, 100, 30)

def hello():

    print 'hello everybody'

widget.connect(close, QtCore.SIGNAL('clicked()'), hello)

widget.show()
sys.exit(app.exec_())

PyQt - QPushButton