How to debug an unfired tkinter event?

[Peter Otten]

jfong at ms4.hinet.net wrote:

> Peter Otten at 2017-10-19 UTC+8 PM 3:24:30 wrote:
>> It's not clear to me what you mean with this. Did you place the table
>> from the recipe elsewhere inside a window that you created or did you
>> make changes in the recipe's code?
> 
> Thank you, Peter. I am using Python 3.4.4 under WinXP.
> 
> When running the file directly from download, I get a table scrolling
> vertically only. If its Table class's __init__ parameter
> "scroll_horizontally" changed to True, it can be scrolled horizontally
> also. But there is a problem when scrolled horizontally, the header field
> will not align with data field anymore. I make some modifications to make
> it does. So far so good.
> 
> Later, I want to make the table also has a vertical header. The first step
> I had taken was to move all 2nd top-level widgets(not much, just four) to
> right one column further to make room for this new widget. I though it's a
> simple work, just increase their grid column value by 1. But Murphy's Law
> comes, the xscrollbar even don't show up when the table was squeezed
> horizontally.

Thank you for the clarification; I understand your problem much better now.

> 
>> > The canvas has a binding:
>> >         self.canvas.bind('<Configure>', self._on_canvas_configure)
>> > 
>> > After this movement, the callback was only triggered when dragging the
>> > root widget to resize canvas vertically, but not horizontally.
>> > 
>> > Event seems has OS involved(it's MS Windows XP in my case). How to
>> > debug this kind of problem, under pdb?
>> 
>> I don't know, but if you can post a small example script that
>> demonstrates the problem, and you are lucky, someone will see the
>> problem.
> 
> This is a ~5xx lines file and I think it's not fare to ask forum members
> to look through it. So I decide to ask for help on how to debug it,
> instead of the solution.
> 
> I try to change the binding to
>          self.bind_all('<Configure>', self._on_canvas_configure)
> and add a line into the callback
>          print(event.widget)
> 
> I got some info below each time when I squeeze the table:
> .
> .50077776
> .50077776.50712528
> .50077776.50712496
> .50077776.50712464
> .50077776.50712144
> .50077776.50712528.50712560.50782256
> .50077776.50712528.50712560.50782256.50783024
> .50077776.50712528.50712560.50782256
> .50077776.50712528.50712560.50782256.50783024
> 
> How to change these number(is it a widget ID?) to a meaning name?

That's the name of the widget in the underlying tcl/tk. You can specify it 
in Python:

>>> import tkinter as tk
>>> print(tk.Button())
.139817813335904
>>> print(tk.Button(name="mybutton"))
.mybutton

You have to ensure that names are unique.