this is the current state of my subclass and args_converter.

gistfile1.txt

class MyCompositeListItem(CompositeListItem):

    def __init__(self, **kwargs):
        super(MyCompositeListItem, self).__init__(**kwargs)
        is_selected = kwargs['is_selected']
##########

def my_args_converter(row_index, rec):
    dict = {'text': '',
            'is_selected': rec.is_selected,
            'padding_x': 100,
            'halign': 'left',
            'size_hint_y': None,
            'cls_dicts': [{'cls': ImageButton, 'kwargs': {'is_selected': rec.is_selected,'source': '/home/clyde/' + rec[3], 'size_hint': (.175,1),
                 'border_color': [0,0,0,1], 'deselected_color': [0,0,3,1], 'selected_color': [0, 6,.0,1], 'on_release' : callback}},
                         {'cls': ListItemLabel,
                         'kwargs': {'text': (rec[0])+', '+ rec[1], 'font_size': 24,
                         'padding_x': -100, 'text_size': (300,60),
                         'halign': 'left'}}]}
    return dict