stop_watch.py

import tkinter as Tkinter
from datetime import datetime
counter = 66600
running = False
def counter_label(label):
	def count():
		if running:
			global counter

		
			if counter==66600:			
				display="Starting..."
			else:
				tt = datetime.fromtimestamp(counter)
				string = tt.strftime("%H:%M:%S")
				display=string

			label['text']=display # Or label.config(text=display)

			
			label.after(1000, count)
			counter += 1

	
	count()	


def Start(label):
	global running
	running=True
	counter_label(label)
	start['state']='disabled'
	stop['state']='normal'
	reset['state']='normal'

def Stop():
	global running
	start['state']='normal'
	stop['state']='disabled'
	reset['state']='normal'
	running = False


def Reset(label):
	global counter
	counter=66600

	
	if running==False:	
		reset['state']='disabled'
		label['text']='Welcome!'

	
	else:			
		label['text']='Starting...'

root = Tkinter.Tk()
root.title("Stopwatch")


root.minsize(width=250, height=70)
label = Tkinter.Label(root, text="Welcome!", fg="black", font="Verdana 30 bold")
label.pack()
f = Tkinter.Frame(root)
start = Tkinter.Button(f, text='Start', width=6, command=lambda:Start(label))
stop = Tkinter.Button(f, text='Stop',width=6,state='disabled', command=Stop)
reset = Tkinter.Button(f, text='Reset',width=6, state='disabled', command=lambda:Reset(label))
f.pack(anchor = 'center',pady=5)
start.pack(side="left")
stop.pack(side ="left")
reset.pack(side="left")
root.mainloop()