Working with 2 displays

[jims]

Thanks for your reply as requested here is a similar program
In this case I want the secondary screen to be filled with red, yellow or green
depending on the button pushed on the GUI which should only be seen on the main display

from tkinter import *

def red():
    root3['bg']="red"
def green():
    root3['bg']="green"
def yellow():
    root3['bg']='yellow'

root = Tk()
root3 = Toplevel(root)
root3.attributes("-fullscreen", True)

Button1 = Button(root,text="RED",command=red)
Button1.pack()

Button2 = Button(root,text="YELLOW",command=yellow)
Button2.pack()

Button3 = Button(root,text="GREEN",command=green)
Button3.pack()
root.mainloop()