Get the index under the position of the given MouseEvent

        :param event: the mouse event
        :type event: :class:`QtGui.QMouseEvent`
        :returns: the index
        :rtype: :class:`QtCore.QModelIndex`
        :raises: None

def index_at_event(self, event):
        """Get the index under the position of the given MouseEvent

        :param event: the mouse event
        :type event: :class:`QtGui.QMouseEvent`
        :returns: the index
        :rtype: :class:`QtCore.QModelIndex`
        :raises: None
        """
        # find index at mouse position
        globalpos = event.globalPos()
        viewport = self.viewport()
        pos = viewport.mapFromGlobal(globalpos)
        return self.indexAt(pos)