title: How to add custom button to a QMessageBox in PyQt4
body: <p>I am coding a application which needs a custom buttons in QMessageBox. i managed to create an example in QT designer which is given below.</p>
  
  <p><img src="https://i.stack.imgur.com/QrLJ6.jpg" alt="enter image description here"></p>
  
  <p>i wanted to do this in a QMessageBox.</p>
  
  <p>I am using python 2.6.4 and PyQt4. please, can any one help.</p>