While adapting my application to the new 0.4.1 (Maemo Fremantle) release, I hit
a possible bug (I mean, everything used to work just fine with PySide 0.3.x); I
attached a sample code to this message which triggers this error:

Error calling slot "openSubWin"
Traceback (most recent call last):
  File "pyside-example.py", line 21, in openSubWin
    self.subWindow.show()       
NotImplementedError: pure virtual method 'QAbstractListModel.rowCount()' not
implemented.
Traceback (most recent call last):
  File "pyside-example.py", line 65, in <module>
    sys.exit(app.exec_())
NotImplementedError: pure virtual method 'QAbstractListModel.rowCount()' not
implemented.

The offending line is number 53 in function "data":

    def data(self,index = QModelIndex(),role = Qt.DisplayRole):
----> if index.isValid() & (index.row() >= 0) & (index.row() <
index.model().rowCount()): <----
            if role == Qt.DisplayRole:
                return self.__items[index.row()]
            else:
                return None
        else:
            return None

accessing the data model using index.model() seems to cause the vanishing of
the (re)definition of the "rowCount" method; if we change the line in:

   if index.isValid() & (index.row() >= 0) & (index.row() < self.rowCount()):

it works as expected, but sometimes this is not possible (inside a custom item
delegate class, for example, its methods receive a QModelIndex instance as a
parameter, and I need its model() property to properly work).

--------

Just to add some detail: there are situations when calling the rowCount()
method through QModelIndex.model() works just fine, the error (if it turns to
be an error) seems to be limited to instances of subclasses of
QAbstractListModel and QStyledItemDelegate.