[Tkinter-discuss] Python 3.2 and binding Mousewheel on Mac

[Ned Deily]

In article <4F941CF1.9040900 at codebykevin.com>,
 Kevin Walzer <kw at codebykevin.com> wrote:
> In order to call this a bug in Tk itself rather than a bug in Tkinter, I 
> need someone to put together a Tcl script that reproduces the issue. 
> Then I can proceed with investigating how to fix it. That's how we 
> proceeded with the text input bug. In this case, however, all evidence 
> suggests that the bug occurs at the level of Tkinter/Tk interaction, and 
> all evidence also suggests that a workaround or fix can--and, most 
> likely should--be implemented on the Python side of the bridge.

As I understand it, Tkinter uses the Tcl C API to add a new command 
which is bound to all events of interest; that's how Tkinter gets called 
back from Tcl.  There are two different interfaces for externaI C 
programs to register as commands; Tkinter still uses the older 
Tcl_CreateCommand interface.  I believe the bug is in how the event 
callback is being set up for the mouse_wheel event.  It might not be 
visible from a Tcl script.  One way to attempt to reproduce it would be 
to write a simple C program that calls Tcl_CreateCommand to create a new 
command and then define a Tcl script that binds mouse_wheel events to it.

http://www.tcl.tk/man/tcl8.5/TclLib/CrtCommand.htm

-- 
 Ned Deily,
 nad at acm.org