Tk mouse wheel events?

[Edward K. Ream]

I am trying to get a binding to fire when the mouse wheel moves.  Vertical
scrolling is handled automatically by the Tk.Text widget, and I would like
to scroll a canvas.  The canvas is in a toplevel that includes Text widgets.

>From a Google search it appears that Button-4 and Button-5 events might do
the job. I don't see this documented on the Tk man pages though.

The following doesn't seem ever to call the event handlers, no matter what
kind of widget is used:

widget.bind("<Button-4>",self.OnButton4)
widget.bind("<Button-5>",self.OnButton5)

Does anyone have any advice or example code?  Thanks!

Edward
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Edward K. Ream   email:  edream at tds.net
Leo: Literate Editor with Outlines
Leo: http://personalpages.tds.net/~edream/front.html
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