Tk: Temporarily change cursor?

[Greg Ewing]

Is there an easy way to temporarily change the
cursor in Tk while a piece of code runs? Or
even a hard way that always works?

There doesn't seem to be any way to directly
change the cursor currently displayed -- you
have to change the cursor of a particular widget.

I've had some success with changing the cursor
of a widget and then doing an update, but it
only works reliably if I pick exactly the right
widget, which is difficult, especially if the
spot in the code where I want to do this is
far removed from the user action which
initiated it.

This is such a commonly done thing, surely
there must be some provision for it in Tk?

Windows, Python 1.5.2 and Tk 8.0, by the way.

Thanks for any help,
Greg