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Editorial Team
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Asked: 2026-06-01T16:47:49+00:00

I have a GUI application written with python+tkinter. In my workflow, I generally start

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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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  1. Editorial Team

    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

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