Tkinter listbox clicking problem

Russell E. Owen owen at nospam.invalid
Fri Sep 13 21:55:29 CEST 2002

In article <sGog9.307183$aA.53945 at sccrnsc02>,
 "Matthew Bonig" <mbonig at> wrote:

>Right now I have it bound so when a Tkinter listbox gets a <Button-1>
>(lb.bind("<Button-1>", someFunc)) it calls function someFunc. Now,
>someFunc() simply prints the curselection(). The problem is it's lagged...
>if I first select list item 1 (index 0), and then 2, and then 3 (array
>indexes 0,1,2) it prints out themout incorrectly.
>(I have someFunc actually do some try, except stuff so I don't get uncaught
>exceptions) Instead of printing 0,1,2 it prints "nothing selected", 0, 1.
>The function get's called before the listbox updates it's selection markers!
>Does anybody know how I could force listbox to update it's selection markers
>so instead of printing "nothing selected, 0,1  it prints 0,1,2 like it

I'm hoping somebody has better ideas, but here are some to try:

Call update_idletasks before you ask for the selection. I have no idea 
if this will work, but it might.

An ugly solution that would probably work:
- extract the y coordinate from the event callback
- call nearest(y_coord) to get the item closest to the mouse click
- explicitly select that index item. You could try skipping this step, 
but you risk a possible error between what you think they clicked on and 
what is hightlighted. Unfortunately, this step will may be a real pain 
for a list that supports multiple selected items.

Poll for selection changes -- thus it may take a bit of time before your 
code notices a change, but it will always be right once it gets there.

-- Russell

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