[PySimpleGUI] update listbox not working

[zappfinger]

I am trying to update a listbox in PySimpleGUI.I have a listbox with a key, so I use this code:

1 2	test=['aaaa','bbbb','cccc'] window.FindElement('_OUTPUT_').Update(values=test)

I get this error:
window.FindElement('_OUTPUT_').Update(values=test)
File "/Users/richard/anaconda/lib/python3.5/site-packages/PySimpleGUI/PySimpleGUI.py", line 719, in Update
self.TKListbox.delete(0, 'end')
AttributeError: 'NoneType' object has no attribute 'delete'

It is as if the listbox with '_OUTPUT_' key is not found...

[zappfinger]

Here is the full code:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

import PySimpleGUI as sg from SQLiteClient import *   ########################## name = 'Pi3B+' ########################## conf = db() otherIP = conf.select('select IP from nodes where name="%s" ' % name)[0][0] layout = [     [sg.Listbox(values=[], key='_OUTPUT_', size=(30, 6))],     [sg.Submit(), sg.Cancel()]      ] window = sg.Window('ToDo').Layout(layout) clint = client(otherIP, 8889) clint.sendSQL('select first_name from employees') ret = clint.checkQ() print(ret)   test=['aaaa','bbbb','cccc'] window.FindElement('_OUTPUT_').Update(values=test) button, values = window.Read()

And here is the output:
/Users/richard/anaconda/bin/python3.5 /Users/richard/PycharmProjects/ToDo/todos.py
config.sqlite
config.sqlite
SQLiteClient clienting on ('0.0.0.0', 8889)
[['Jim'], ['Jim'], ['Jim'], ['John'], ['Susan']]
Traceback (most recent call last):
File "/Users/richard/PycharmProjects/ToDo/todos.py", line 24, in <module>
window.FindElement('_OUTPUT_').Update(values=test)
File "/Users/richard/anaconda/lib/python3.5/site-packages/PySimpleGUI/PySimpleGUI.py", line 719, in Update
self.TKListbox.delete(0, 'end')
AttributeError: 'NoneType' object has no attribute 'delete'

[zappfinger]

Apparently I had to use Finalize() on the layout line, like this:

1	window = sg.Window('ToDo').Layout(layout).Finalize()

Since the window is not fully formed until then...