Qt QGraphicsView - tooltips don't appear

I'm creating a 2D view in PyQt using the QGraphicsView. Unfortunately, I can't seem to find any way of getting tooltips to appear at any level - on QGraphicsItems, QGraphicsItemGroups, etc.

It's getting to the point where they'd be very useful, but I have tried:

1. Setting the tooltips using setToolTip().
2. Using setAttribute(QtCore.Qt.WA_AlwaysShowToolTips) on the QGraphicsView

The second I thought would be a dead-cert, but appears to do nothing at all...

This seems to work as expected using python Qt 4.8.7 with PyQt 4.11.4:

from PyQt4 import QtGui

class Window(QtGui.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.view = QtGui.QGraphicsView(self)
        self.view.setScene(QtGui.QGraphicsScene(self))
        for index, name in enumerate('One Two Three Four Five'.split()):
            item = QtGui.QGraphicsRectItem(index * 60, index * 60, 50, 50)
            item.setToolTip('Rectangle: ' + name)
            self.view.scene().addItem(item)
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.view)

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.resize(400, 400)
    window.show()
    sys.exit(app.exec_())

Presumably, there must be something different in your own code that is compromising the normal behaviour. But that will be impossible to identify without a proper test case.