from tkinter import *

root = Tk()

Grid.rowconfigure(root, 0, weight=1)
Grid.columnconfigure(root, 0, weight=1)

frame=Frame(root)
frame.grid(row=0, column=0, sticky=N+S+E+W)

Grid.rowconfigure(frame, 0, weight=1)

Grid.columnconfigure(frame, 0, weight=1)
btn = Button(frame, text="open")
btn.grid(row=0, column=0, sticky=N+S+E+W)
Grid.columnconfigure(frame, 1, weight=1)
btn = Button(frame, text="close")
btn.grid(row=0, column=1, sticky=N+S+E+W)

root.mainloop()