# test polymorphism

import board
import displayio
import terminalio
import time

from adafruit_display_text import label

class GridLabel(label.Label):
    def __init__(self, font, **kwargs):
        super().__init__(font, **kwargs)

    @property
    def x(self):
        return super().x

    @x.setter
    def x(self, value):
        # Round down to the nearest 10 grid
        xx = (value // 10) * 10

        # If Python properly implemented polymorphism the following would work:
        #
        # super().x = xx
        #
        # Unfortunately, thanks to a bug unfixed for 9 years
        # Ref: https://bugs.python.org/issue14965
        # we need to do this
        super(self.__class__, self.__class__).x.__set__(self, xx)

    @property
    def y(self):
        return super().y

    @y.setter
    def y(self, value):
        # Round down to the nearest 10 grid
        yy = (value // 10) * 10

        # If Python properly implemented polymorphism the following would work:
        #
        # super().y = yy
        #
        # Unfortunately, thanks to a bug unfixed for 9 years
        # Ref: https://bugs.python.org/issue14965
        # we need to do this
        super(self.__class__, self.__class__).y.__set__(self, yy)


def main():
    global board
    if hasattr(board, 'DISPLAY'):
        display = board.DISPLAY
    else:
        from adafruit_blinka import board
        from blinka_displayio_pygamedisplay import PyGameDisplay
        # The key here is "auto_refresh=False". Failing to do so will create a new thread
        # for the rendering, and macOS (or the Python implementation for it) can only be
        # performed on the main (UI) thread.
        display = PyGameDisplay(width=320, height=240, auto_refresh=False)

    splash = displayio.Group(max_size=10)
    display.show(splash)

    WIDTH = display.width
    HEIGHT = display.height
    print(f"Display: {WIDTH}x{HEIGHT}")

    # Draw a black background
    bg_bitmap = displayio.Bitmap(WIDTH, HEIGHT , 1)
    bg_palette = displayio.Palette(1)
    bg_palette[0] = 0x000000
    splash.append(displayio.TileGrid(bg_bitmap, pixel_shader=bg_palette))

    sample = GridLabel(terminalio.FONT,
                       text="Polymorph",
                       color=0xFFFFFF,
                       scale=2,
                       x=0,
                       y=0)
    splash.append(sample)

    while True:
        for x in range(0, HEIGHT):
            sample.x = x
            sample.y = x
            print(f"Asked for{x}X{x}  Got {sample.x}X{sample.y}")
            if hasattr(display, 'refresh'):
                display.refresh()
            time.sleep(0.02)
        pass

main()

Adafruit CircuitPython 6.2.0-beta.2 on 2021-02-11; Adafruit PyPortal with samd51j20
>>> %Run -c $EDITOR_CONTENT
Display: 320x240
Traceback (most recent call last):
  File "<stdin>", line 95, in <module>
  File "<stdin>", line 76, in main
  File "<stdin>", line 12, in __init__
  File "/lib/adafruit_display_text/label.py", line 107, in __init__
  File "<stdin>", line 30, in x
ValueError: Must be a Group subclass.

// Helper to ensure we have the native super class instead of a subclass.
displayio_group_t* native_group(mp_obj_t group_obj) {
    mp_obj_t native_group = mp_instance_cast_to_native_base(group_obj, &displayio_group_type);
    if (native_group == MP_OBJ_NULL) {
        mp_raise_ValueError_varg(translate("Must be a %q subclass."), MP_QSTR_Group);
    }
    mp_obj_assert_native_inited(native_group);
    return MP_OBJ_TO_PTR(native_group);
}