Example of how to read input and show it in an another input box

output_from_input.py

import PySimpleGUI as sg

# The Window layout definition
# Pay close attention to the two Input Elements, they each have a key identifier
layout = [  [sg.Text('Test Program For StackOverflow') ],
            [sg.T('Enter stuff here'), sg.Input(key='_in_')],
            [sg.T('and it will show up here'), sg.Input(key='_out_')],
            [ sg.Button('OK')]  ]

# Make a window
window = sg.Window('My window',
                   default_element_size=(20,1),
                   auto_size_text=False,
                   return_keyboard_events=True,
                   text_justification='right').Layout(layout)

# Event loop - show window and read the input values
while True:
    button, values = window.Read()
    window.FindElement('_out_').Update(values['_in_'])   # write whatever's in input to output

Here is the output from the program.