Tkinter ttk Treeview binding responds to past events!
John O'Hagan
research at johnohagan.com
Tue Sep 12 19:40:31 EDT 2023
On Tue, 2023-09-12 at 20:51 +0200, Mirko via Python-list wrote:
> Am 12.09.23 um 07:43 schrieb John O'Hagan via Python-list:
>
> > My issue is solved, but I'm still curious about what is happening
> > here.
>
> MRAB already said it: When you enter the callback function, Tk's
> mainloop waits for it to return. So what's happening is:
>
> 1. Tk's mainloop pauses
> 2. temp_unbind() is called
> 3. TreeviewSelect is unbound
> 4. events are queued
> 5. TreeviewSelect is bound again
> 6. temp_unbind() returns
> 7. Tk's mainloop continues with the state:
> - TreeviewSelect is bound
> - events are queued
>
> [. . .]
Thanks (also to others who have explained), now I get it!
> FWIW, here's a version without after(), solving this purely on the
> python side, not by temporarily unbinding the event, but by
> selectively doing nothing in the callback function.
>
> from tkinter import *
> from tkinter.ttk import *
>
> class Test:
> def __init__(self):
> self.inhibit = False
> root=Tk()
> self.tree = Treeview(root)
> self.tree.pack()
> self.iid = self.tree.insert('', 0, text='test')
> Button(root, command=self.temp_inhibit).pack()
> mainloop()
>
> def callback(self, *e):
> if not self.inhibit:
> print('called')
>
> def temp_inhibit(self):
> self.inhibit = True
> self.tree.selection_set(self.iid)
> self.tree.selection_remove(self.iid)
> self.tree.selection_set(self.iid)
> self.inhibit = False
> self.callback()
>
> c=Test()
>
I like this solution better - it's much more obvious to me what it's
doing.
Regards
John
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