Replaces occurrences of find_string with replace_string at findpos

        and marks content as changed

        Parameters
        ----------

        findpositions: List of 3-Tuple of Integer
        \tPositions in grid that shall be replaced
        find_string: String
        \tString to be overwritten in the cell
        replace_string: String
        \tString to be used for replacement

def replace_all(self, findpositions, find_string, replace_string):
        """Replaces occurrences of find_string with replace_string at findpos

        and marks content as changed

        Parameters
        ----------

        findpositions: List of 3-Tuple of Integer
        \tPositions in grid that shall be replaced
        find_string: String
        \tString to be overwritten in the cell
        replace_string: String
        \tString to be used for replacement

        """
        # Mark content as changed
        post_command_event(self.main_window, self.ContentChangedMsg)

        for findpos in findpositions:
            old_code = self.grid.code_array(findpos)
            new_code = old_code.replace(find_string, replace_string)

            self.grid.code_array[findpos] = new_code

        statustext = _("Replaced {no_cells} cells.")
        statustext = statustext.format(no_cells=len(findpositions))

        post_command_event(self.main_window, self.StatusBarMsg,
                           text=statustext)

        self.grid.ForceRefresh()