Present two stimuli simultaneously but in different time frames

Coding
1

Hi, I am trying to present two types of stimuli. The first type is pictures which I would like to present them 10 frames each (they are stored in “images”). And on top of the picture, I want to present a black cross (which is consisted of “line1” and “line2”), and for five periods of time it will change to a white cross (“line3” and “line4”) for 12 frames. The total length of the trial will be 2160 frames. I stored the beginning of five times that the cross will change to white in “white_onset_time” and my code for present the stimuli is :

frameN = -1
for stim in images:
    for frameN in range(10): 
        stim.draw()
        line1.draw()
        line2.draw()
        for k in range(5):
            for frameN in range(2160):
                while white_onset_time[k] <= frameN < white_onset_time[k]+12:
                    line3.draw()
                    line4.draw()
                    frameN +=1
        win.flip()

It does not look right. I am wondering where goes wrong. Thank you!