PyQt how to make a toolbar button appeared as pressed

I want to make a specific button in PyQt toolbar appeared as pressed(with blue background). Suppose when I hit the toolbar button I want it to be appeared as pressed

import sys
from PyQt4 import QtGui, QtCore
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class Window(QtGui.QMainWindow):   
    def __init__(self):
        super(Window, self).__init__()
        self.setGeometry(50, 50, 700, 700)
        self.setWindowTitle('Rich Text Editor')
        self.statusBar = QStatusBar()
        self.textEdit = QtGui.QTextEdit()
        self.setCentralWidget(self.textEdit)
        self.setStatusBar(self.statusBar)
        self.home()

    def home(self):
        changeBoldActionTB = \
        QtGui.QAction(QtGui.QIcon('bold-text-option.png'),
                      'Make the text bold', self)
        changeBoldActionTB.triggered.connect(self.changeBold)

        self.formatbar = QToolBar()
        self.addToolBar(Qt.TopToolBarArea, self.formatbar)
        self.formatbar.addAction(changeBoldActionTB)
        self.show()

    def changeBold(self):
         pass
         #I think this does't matter        

def run():
    app = QtGui.QApplication(sys.argv)
    GUI = Window()
    sys.exit(app.exec_())

run()

I have two toolbars.I am planning to use cursorPositionChanged to do this but still is there a way in PyQt to do this

reproduible code: https://files.fm/u/h4c2amdx

Solution

Instead of using QAction you must use QToolButton and set the checkable property to True:

toolButton.setCheckable(True)

Example:

class Window(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)
        self.setWindowTitle('Rich Text Editor')
        self.statusBar = QStatusBar(self)
        self.textEdit = QtGui.QTextEdit(self)
        self.setCentralWidget(self.textEdit)
        self.setStatusBar(self.statusBar)

        self.home()

    def home(self):
        toolButton = QToolButton(self)
        toolButton.setIcon(QtGui.QIcon('bold-text-option.png'))
        toolButton.setCheckable(True)
        toolButton.toggled.connect(self.onToggled)

        self.formatbar = QToolBar(self)
        self.addToolBar(Qt.TopToolBarArea, self.formatbar)
        self.formatbar.addWidget(toolButton)

    def onToggled(self, checked):
        print(checked)

Screenshots:

Plus: To set the value manually and to obtain the status the following instructions are used:

toolButton.setChecked(True) # set State
print(toolButton.isChecked()) # get State
toolButton.toggle() # change state