In Glyphsapp, find the ymin and ymax in all layers

ymin_ymax.py

#MenuTitle: Find Family ymin and ymax
def shortest_tallest_glyphs(font, *args):
    '''find the tallest and shortest glyphs in all masters from a list.
    If no list is given, search all glyphs.'''
    lowest = 0.0
    highest = 0.0
    highest_name = ''
    lowest_name = ''

    masters_count = len(font.masters)

    if args:
        glyphs = [font.glyphs[i] for i in args]
    else:
        glyphs = font.glyphs

    for glyph in glyphs:
        for i in range(masters_count):
            glyph_ymin = glyph.layers[i].bounds[0][-1]
            glyph_ymax = glyph.layers[i].bounds[-1][-1] + glyph.layers[i].bounds[0][-1]
            if glyph_ymin < lowest:
                lowest = glyph_ymin
                lowest_name = glyph.name
            if glyph_ymax > highest:
                highest = glyph_ymax
                highest_name = glyph.name
    return (lowest_name, lowest, highest_name, highest)

def main():
    local_font = Glyphs.font
    print shortest_tallest_glyphs(local_font)


if __name__ == '__main__':
    main()