Widgets not showing up on a Grid layout (PySide)

Question

I have some code that displays a few widgets in the window. The widgets, however do not appear on the window:

#!/usr/bin/python
import sys
from PySide import QtGui

class Window(QtGui.QMainWindow):
  def __init__(self):
    super(Window,self).__init__()
    self.initUI()
  def initUI(self):
    self.setGeometry(200,500,400,400)
    self.setWindowTitle("A Grid Layout")
    l1 = QtGui.QLabel("Label 1")
    l2 = QtGui.QLabel("Label 2")
    l3 = QtGui.QLabel("Label 3")
    le1 = QtGui.QLineEdit()
    grid = QtGui.QGridLayout()
    grid.setSpacing(10)
    grid.addWidget(l1,1,0)#widget,row,column
    grid.addWidget(l2,2,1)
    grid.addWidget(l3,3,2)
    grid.addWidget(le1,4,0,1,2)#row,column span
    self.setLayout(grid)#sets layout
    self.show()

def main():
  app = QtGui.QApplication(sys.argv)
  win = Window()
  exit(app.exec_())

if __name__ == "__main__":
  main()

I'm new to layouts in PySide so any help is much appreciated.

Answer 1

A QMainWindow isn't supposed to be used with a layout, but with a central widget containing it's content. Try this:

#!/usr/bin/python
import sys
from PySide import QtGui

class Window(QtGui.QMainWindow):
  def __init__(self):
    super(Window,self).__init__()
    self.initUI()
  def initUI(self):
    self.setGeometry(200,500,400,400)
    self.setWindowTitle("A Grid Layout")
    l1 = QtGui.QLabel("Label 1")
    l2 = QtGui.QLabel("Label 2")
    l3 = QtGui.QLabel("Label 3")
    le1 = QtGui.QLineEdit()
    grid = QtGui.QGridLayout()
    grid.setSpacing(10)
    grid.addWidget(l1,1,0)#widget,row,column
    grid.addWidget(l2,2,1)
    grid.addWidget(l3,3,2)
    grid.addWidget(le1,4,0,1,2)#row,column span

    centralWidget = QtGui.QWidget()
    centralWidget.setLayout(grid)
    self.setCentralWidget(centralWidget)

    self.show()

def main():
  app = QtGui.QApplication(sys.argv)
  win = Window()
  exit(app.exec_())

if __name__ == "__main__":
  main()