python tkinter binding: How to prevent double events

This requires one of Tkinter's little known quirks, i.e. you have to return "break" from a function. The program below rebinds the key to the "ignore()" function that returns "break". I don't understand how or why this is, and it is documented http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm and does work.

import sysif sys.version_info[0] < 3:    import Tkinter as tk     ## Python 2.xelse:    import tkinter as tk     ## Python 3.xclass App:    def __init__(self, master): # Constructor        self.master=master        self.counter=0        # build GUI        self.label = tk.Label(text="Press <space>", width=40)        self.label.grid(row=1, column=1, sticky='w')        # bind keys to buttons        master.bind('<Key-space>', self.keyPressed)    def ignore(self, event):        print "ignore"        return "break"    def keyPressed(self, event):        self.master.bind('<Key-space>', self.ignore)        print("Step 1")        self.counter = self.counter + 1        self.label["text"] = str(self.counter)        self.master.after(3000, self.bindit)        print("Step  2")    def bindit(self):        self.master.bind('<Key-space>', self.keyPressed)        print("Step 3 = ready for more input")root = tk.Tk()root.option_add('*font', ('Arial', 11, 'bold'))# root.attributes("-toolwindow", 1)posX = root.winfo_screenwidth() - 500posY = 30root.geometry("+%d+%d" % (posX, posY))root.title("Bind tester")display = App(root)root.mainloop()

Probably the time.sleep method is messing with Tkinter mainloop.You should use the 'after' method from Tkinter module.

http://infohost.nmt.edu/tcc/help/pubs/tkinter/web/universal.html

If you do not pass a callback argument, this method waits delay_ms milliseconds, as in the .sleep() function of the standard Python time module.

Check this post for an example:

Python time.sleep