Create a gradient widget using only the tkinter library.
Create an instance of GradientFrame passing as a parameter the frame where it will be placed.
In addition to the Canvas settings, you can also configure the colors and direction of the gradient.
from GradientFrame import GradientFrame
from tkinter import Tk
root = Tk()
gf = GradientFrame(root, colors = ("yellow", "black"), width = 800, height = 600)
gf.config(direction = gf.top2bottom)
gf.pack()
root.mainloop()