How to debug an unfired tkinter event?

[Peter Otten]

jfong at ms4.hinet.net wrote:

> Peter Otten於 2017年10月19日星期四 UTC+8下午6時04分39秒寫道：
>> 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.
> 
> Thank you. It's very helpful information.
> 
> By the way, I just found this problem can be easily seen by not modifing
> the original file too much with the following steps:
> 
> 1. copy and get the file from the link.
> 2. change the "scroll_horizontally" parameter in the "Table" class's
> __init__ method to "True"
> 
> Running it you will see it perform correctly.
> 
> 3. Change the "column=x" at line 268, 282, 288, 292, 303 to "column=x+1"
> 
> Now it has the problem.

There may be other less obvious places that are affected by your 
modifications. Does changing

self.grid_columnconfigure(0, weight=1)

to

self.grid_columnconfigure(1, weight=1)

in Table.__init__() help?