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Asked: 2026-05-24T00:45:52+00:00

I’m proposing a continuation of the discussion in disable tkinter keyboard shortcut : I

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I’m proposing a continuation of the discussion in disable tkinter keyboard shortcut: I have an event handler for an event that Tkinter also uses, so that my prog & Tkinter interact badly.

Since it is a problem that I’ve been unable to solve I’m re-proposing here, where I tried to boil it down to the simplest form in the following code:

#!/usr/bin/env python

from Tkinter import *
import tkFont

def init():
    global root,text

    root = Tk()
    root.geometry("500x500+0+0")
    dFont=tkFont.Font(family="Arial", size=10)

    text=Text(root, width=16, height=5, font=dFont)
    text.pack(side=LEFT, fill=BOTH, expand = YES)

    root.bind("<Control-b>", setbold)

    text.tag_config("b",font=('Verdana', '10', 'bold' ))
    text.tag_config("i",font=('Verdana', '10', 'italic' ))

def removeformat(event=None):
    text.tag_remove('b',SEL_FIRST,SEL_LAST)
    text.tag_remove('i',SEL_FIRST,SEL_LAST)

def setbold(event=None):
    removeformat()
    text.tag_add('b', SEL_FIRST,SEL_LAST)
    text.edit_modified(True)

def main():
    init()        
    mainloop()


if __name__ == '__main__':
    main()

What it should do is simply to produce a text window where you write into.
Selecting some text and pressing Ctrl+B the program should remove any preexisting tag, then assign to it the ‘b’ tag that sets the text to bold.

What instead happens is an exception at the first tag_remove, telling me that text doesn't contain any characters tagged with "sel".

The suggestion to use a return 'break' is of no use, since the selection disappears before setbold() has any chance to act…

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1 Answer

  1. Editorial Team

    Set your binding on the text widget, not on the root. (Whole toplevel bindings are processed after widget class bindings – where the standard <Control-Key-b> binding is – and those are processed after the widget instance bindings, which is what you want to use here.) And you need to do that 'break'; it inhibits the subsequent bindings. (If you’re having any problems after that, it’s probably that the focus is wrong by default, but that’s easy to fix.)

    The only other alternative is to reconfigure the bindtags so that class bindings are processed after toplevel bindings, but the consequences of doing that are very subtle and far-reaching; you should use the simpler approach from my first paragraph instead as that’s the normal way of handling these things.

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