tkclock.py

from Tkinter import *
from time import strftime

class Clock: ##Tkinter is best used as a class object. Makes life easier.
    def __init__(self):
        self.root = Tk()
        self.root.title("Clock")
        self.root.protocol("WM_DELETE_WINDOW", self.quitting) ## handle my own exit code.
        ##set position to be center of screen
        window_width = 1100
        window_height = 400
        ws = self.root.winfo_screenwidth() # width of the screen
        hs = self.root.winfo_screenheight() # height of the screen
        x = (ws/2)-(window_width/2)
        y = (hs/2)-(window_height/2)
        self.root.geometry("%sx%s+%s+%s" %(window_width, window_height, int(x), int(y)))
        ##
        # set window to pop up above others
        self.root.attributes("-topmost", True)
        self.root.attributes("-topmost", False)
        ##
        self.quit = False
        self.curtime = ""
    def update_time(self):
        self.curtime = strftime("%I:%M:%S")
    def run(self):
        display = Label(self.root, font="arial 200 bold", bg="blue violet", fg="lime green")
        display.pack(fill=BOTH, expand=1) # personal preference, i dont like grid()
        while not self.quit:
            self.update_time()
            display.configure(text=self.curtime)
            self.root.update()
            self.root.update_idletasks()
    def quitting(self):
        print("I clicked the X button. i can quit any running processes here.")
        self.quit=True

if __name__ == "__main__":
    try:
        app = Clock()
        app.run()
    except Exception as err:
        print(err)
        print("quitting")