Add QWidget to QListWidget

If you use PyQt5, there is some changes, you must use QtWidgets for widget not QtGui. Use this code if using with PyQt5:

Don't forget to import PyQt5:

from PyQt5 import QtCore, QtGui, QtWidgets`

itemN = QtWidgets.QListWidgetItem()
# Create widget
widget = QtWidgets.QWidget()
widgetText = QtWidgets.QLabel("I love PyQt!")
widgetButton = QtWidgets.QPushButton("Push Me")
widgetLayout = QtWidgets.QHBoxLayout()
widgetLayout.addWidget(widgetText)
widgetLayout.addWidget(widgetButton)
widgetLayout.addStretch()

widgetLayout.setSizeConstraint(QtWidgets.QLayout.SetFixedSize)
widget.setLayout(widgetLayout)
itemN.setSizeHint(widget.sizeHint())

# Add widget to QListWidget funList
funList.addItem(itemN)
funList.setItemWidget(itemN, widget)

Try this:

itemN = QtGui.QListWidgetItem() 
#Create widget
widget = QtGui.QWidget()
widgetText =  QtGui.QLabel("I love PyQt!")
widgetButton =  QtGui.QPushButton("Push Me")
widgetLayout = QtGui.QHBoxLayout()
widgetLayout.addWidget(widgetText)
widgetLayout.addWidget(widgetButton)
widgetLayout.addStretch()

widgetLayout.setSizeConstraint(QtGui.QLayout.SetFixedSize)
widget.setLayout(widgetLayout)  
itemN.setSizeHint(widget.sizeHint())    

#Add widget to QListWidget funList
funList.addItem(itemN)
funList.setItemWidget(itemN, widget)

As you can see, you need setSizeConstraint to the layout and setSizeHint to item.