from tkinter import *

def upload():
    statusvar.set("Busy....")
    sbar.update()
    import time
    time.sleep(2)
    statusvar.set("Ready Now")

root = Tk()
root.geometry("455x233")
root.title("Status Bar Tutorial")

# STatusbar is not a widget
statusvar = StringVar()
statusvar.set("Ready")
sbar = Label(root, textvariable = statusvar, relief = SUNKEN, anchor = "w")
sbar.pack(side = BOTTOM, fill = X)
Button(root, text = "Upload", command = upload).pack()

root.mainloop()
