closing a "nested" window with a button in PySimpleGUI and repeating this process

[Robby_PY]

As you use windows and not popups you have to catch signals from all windows.
Your code works with minor changes (I changed the "rc= reverseComplement(seq)" as I don't know what it does)

import PySimpleGUI as sg
 
sg.theme('DarkAmber')
 
layout = [[sg.Text('Reverse complement:', size=(15,1), key='-OUTPUT-')],
          [sg.Input(key='-IN-')],
          [sg.Button('Convert'), sg.Button('Exit'), sg.Button('Help')]]
 
window= sg.Window('Reverse Complement Converter', layout, finalize = True)
 
window_help = None
 
 
while True:
    win, event, values = sg.read_all_windows() # Read all signals from all windows
    if event in (sg.WIN_CLOSED, 'Exit', 'Cancel'):
        if win == window:
            break
        elif window_help and win == window_help:
            window_help.close()
            window_help = None
    elif event == 'Convert':
        seq=values['-IN-']
        rc= "YES!" #reverseComplement(seq)
        window['-OUTPUT-'].update(rc)   
    elif event == "Help":
        layout_help = [[sg.Text("This program requires a DNA sequence as an input and returns the reverse complement")],[sg.Button("Cancel")]]
        window_help = sg.Window("Help", layout_help, finalize = True)
         
window.close()

Thanks for your reply Serafim. Indeed, with your changes I can open and close the help window. Thank you! FYI: reverseComplement is a custom function which processes a string and outputs a string.

I have a few questions though:

1) In line 19 of your code, why did you write

elif window_help and win == window_help:

and not just

elif win == window_help

? I removed the "window_help" in this statement, and the GUI appears to work fine.

2)In the same elif statement as question 1. Why did you add

window_help=None

(line 21). Again, if I delete this line, it seems to work fine.

3)When I click the "Convert" button, the string processed by the reverseComplement function (i.e. "rc" value), should appear to the right of "Reverse complement:" as it is the "key" of this Text. This happend in my initial script. However, when I now press "Convert", the "rc" value replaces the "Reverse complement:" string. Any idea why this happens and how I could fix this? When I look at the code, I fail to understand why it replaces the whole string.

Thanks!