Displays progress and returns True if abort

        Parameters
        ----------

        cycle: Integer
        \tThe current operation cycle
        statustext: String
        \tLeft text in statusbar to be displayed
        total_elements: Integer:
        \tThe number of elements that have to be processed
        freq: Integer, defaults to None
        \tNo. operations between two abort possibilities, 1000 if None

def _is_aborted(self, cycle, statustext, total_elements=None, freq=None):
        """Displays progress and returns True if abort

        Parameters
        ----------

        cycle: Integer
        \tThe current operation cycle
        statustext: String
        \tLeft text in statusbar to be displayed
        total_elements: Integer:
        \tThe number of elements that have to be processed
        freq: Integer, defaults to None
        \tNo. operations between two abort possibilities, 1000 if None

        """

        if total_elements is None:
            statustext += _("{nele} elements processed. Press <Esc> to abort.")
        else:
            statustext += _("{nele} of {totalele} elements processed. "
                            "Press <Esc> to abort.")

        if freq is None:
            show_msg = False
            freq = 1000
        else:
            show_msg = True

        # Show progress in statusbar each freq (1000) cells
        if cycle % freq == 0:
            if show_msg:
                text = statustext.format(nele=cycle, totalele=total_elements)
                try:
                    post_command_event(self.main_window, self.StatusBarMsg,
                                       text=text)
                except TypeError:
                    # The main window does not exist any more
                    pass

            # Now wait for the statusbar update to be written on screen
            if is_gtk():
                try:
                    wx.Yield()
                except:
                    pass

            # Abort if we have to
            if self.need_abort:
                # We have to abort`
                return True

        # Continue
        return False