import RPi.GPIO as GPIO
import Tkinter
GPIO.setup(7,GPIO.OUT)
from Tkinter import *
root = Tk()

def Off(event):
    GPIO.output(7,False)

def On(event):
    GPIO.output(7,True)

btn1 = Button(root,
                text="On",
                width=30,height=5,
                bg="white",fg="black")
btn1.bind("<Button-1>", On)
btn1.pack()

btn2 = Button(root,
                text="Off",
                width=30,height=5,
                bg="white",fg="black")
btn2.bind("<Button-1>", Off)
btn2.pack()
root.mainloop()