Tk mouse wheel events?

[Fredrik Lundh]

Edward K. Ream wrote:

> 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!

from Tkinter import *

def roll(event):
    print event.delta

frame = Frame(width=200, height=200)
frame.pack()
frame.focus_set() # wheel events goes to focussed window
frame.bind("<MouseWheel>", roll)

mainloop()

</F>