I have a GUI application written with python+tkinter. In my workflow, I generally start the gui from the commandline, do some things in the gui and then I find myself navigating to other terminal windows to do some work. Inevitably, I want to shut down the GUI at some point, and out of habit I often just navigate to the terminal that started the GUI and send a KeyboardInterrupt (Ctrl-c). However, This interrupt is not recieved until I raise the GUI window in the Window manager. Does anyone know why this happens? If the gui is started in a single function, is there a simple workaround -- multiprocessing maybe?
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mgilson
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see http://groups.google.com/group/comp.lang.python/browse_frm/thread/714cbada9a364d7e/ebf5db79b469661f?lnk=gst&q=tkinter+signal#ebf5db79b469661f – noob oddy Apr 07 '12 at 06:57
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@nooboddy -- great find. If you post the link as an answer, we can accept it which might make it easier for someone else looking for the same thing to find. – mgilson Apr 08 '12 at 00:10
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"Duplicate": https://stackoverflow.com/questions/13784232/tkinter-keyboardinterrupt-taking-a-while – Udi Mar 22 '22 at 15:33
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from the newsgroups:
I'm using Python 1.5 under Redhat Linux 5.0. I'm trying to figure out the best way to trap a SIGINT (or Ctrl-C) when using tkinter. To illustrate the problem I have, do the following ...
-- Build Python-1.5 with tkinter enabled.
-- Go into the Demo/tkinter/guido directory under the Python-1.5 build tree.
-- Type "python imageview.py image-file", where "image-file" is the full pathname of a displayable image.
-- Once the image pops up, make sure that the window focus is held by the xterm window from which the "python ..." command was just now invoked.
-- Hit Ctrl-C.
At this point, nothing happens. The Ctrl-C seems to be ignored. But now ...
-- Without hitting any more keys on the keyboard, set the window focus to the displayed image window.
As soon as that window gets the focus, the Ctrl-C takes effect.
My question is this: is there any way to restructure the "imageview.py" program so that it will respond to SIGINT (Ctrl-C) immediately, without having to set the window focus to the displayed image first?
Thanks in advance for any help you folks can give me.
---- What you're seeing is caused by the way signal handlers are handled. You're stuck in the Tcl/Tk main loop, and signal handlers are only handled by the Python interpreter. A quick workaround is to use after() to schedule a dummy function to be called once a second or so -- this will make it appear that your signal is handled in a timely manner.--Guido van Rossum
