Qt override.

        Reimplemented from base class to allow the use of custom filtering.

def filterAcceptsRow(self, row_num, parent):
        """Qt override.

        Reimplemented from base class to allow the use of custom filtering.
        """
        model = self.sourceModel()
        name = model.row(row_num).name
        r = re.search(self.pattern, name)

        if r is None:
            return False
        else:
            return True