editor.py

import PySimpleGUI as sg

NUM_ROWS = 20
NUM_COLS = 80

layout = [
            *[[sg.T(f'{i:02} ',background_color='white', text_color = 'gray60'), sg.In(size=(NUM_COLS,1), do_not_clear=True, key=i)] for i in range(NUM_ROWS)],
            [sg.Button('Exit')]
         ]

window = sg.Window('Window Title', element_padding=(0,0), border_depth=0, return_keyboard_events=True).Layout(layout)

focus = 0
while True:             # Event Loop
    event, values = window.Read()
    if event.startswith('Down') or event == '\r':
        focus += (focus < NUM_ROWS-1)
        window.Element(focus).SetFocus()
    elif event.startswith('Up'):
        focus -= (focus > 0)
        window.Element(focus).SetFocus()
    if event is None or event == 'Exit':
        break

window.Close()