[Tkinter-discuss] Stumped

Cam camfarnell at cogeco.ca
Tue Nov 28 18:39:14 CET 2006

This is probably really simple but I haven't yet figured it out. It 
happens in the context of a much larger program but stripped to it's 
essence is per the little program below.

The general idea is that the user clicks on a button, that initiates an 
operation which is going to take some time, so I would like to allow the 
user to press ESCAPE to cancel the operation. In the code below the 
"on_button" function is the one that takes some time, but if the user 
presses ESCAPE while it is running, the escape isn't processed until 
*after* the "on_button" function returns which sort of defeats the 
purpose. I've tried inserting update_idletasks() into the function and 
various other things without success.

Any suggestions? I'm running Python 2.4.2 under Linux.


Cam Farnell

- - - - -

from Tkinter import *
import time

def on_button():
     for J in range(10):
         print J
         if CancelNow:

def Cancel(Event):
     print 'Cancelling now'
     CancelNow = True

Root = Tk()

B = Button(Root,command=on_button,text='Go')
CancelNow = False


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