psychopy.org | Reference | Downloads | Github

Crash with stimulus object code

Hello,
i try to launch the example code from psychoPy web site:

from psychopy import visual, core
win = visual.Window([400,400])
message = visual.TextStim(win, text='hello')
message.autoDraw = True # Automatically draw every frame
win.flip()
core.wait(2.0)
message.text = 'world' # Change properties of existing stim
win.flip()
core.wait(2.0)

i have one error with pyglet and i have to downgrade it and it seems OK.
But Second bug :
raise AssertionError(‘XF86VidModeGetGammaRamp failed’)
AssertionError: XF86VidModeGetGammaRamp failed

i try the solution from djmannion: https://github.com/psychopy/psychopy/issues/2061#issuecomment-428792028
However the problem is not solved.
Any suggestion?
Thanks!