How to Create TopLevel Window in Tkinter 

from tkinter import *
root = Tk()
root.geometry("800x350+450+86")
root.title("Tkinter Top Level")
root.resizable(width="true", height="true")
root.config(bg="#f0f022")

def windowopentop():
           top = Toplevel(root)
           top.mainloop()

btn1 = Button(root, text="Window Open", command=windowopentop, font=("Times new roman", 25, "bold"))
btn1.pack(pady=60)

btn2 = Button(root, text="Exit",font=("Times new roman", 25, "bold"), command=root.quit)
btn2.pack(pady=10)
root.mainloop()

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