title: How can I stretch a single widget in a horizantal layout in PyQt4?
body: <p>Here all three pushbutton are equivalent in size, how to increase size of only first pushbutton so that it occupies more space than other two buttons. </p>
  
  <pre><code>from PyQt4 import QtGui
  import sys
  
  class AllWidgets(QtGui.QWidget):
  
      def __init__(self):
          super(AllWidgets, self).__init__()
          layout = QtGui.QHBoxLayout()
          #code for pushbutton 1
          pushbutton_1 = QtGui.QPushButton()
          pushbutton_1.setText('First')
          layout.addWidget(pushbutton_1)
          #code for pushbutton 2
          pushbutton_2 = QtGui.QPushButton()
          pushbutton_2.setText('Second')
          layout.addWidget(pushbutton_2)
          #code for pushbutton 3
          pushbutton_3 = QtGui.QPushButton()
          pushbutton_3.setText('Third')
          layout.addWidget(pushbutton_3)
          self.setLayout(layout)
  
  if __name__ == '__main__':
      app = QtGui.QApplication(sys.argv)
      display = AllWidgets()
      display.show()
      sys.exit(app.exec_())
  </code></pre>