Preventing Up/Down Arrows from Moving Focus

[Melissa Danforth <mdanfor cs csubak edu>]

Within an entry widget, pressing the up/down arrow keys causes the focus
to shift to the next/previous widget. I have an application where I do not
want this to occur. I noticed that within the text widget, using the up
and down arrow keys does not cause the focus to move, but even after looking
at the source, I cannot find how it does that.

How does one prevent the up/down arrows from shifting the focus? 
For my application, it is probably sufficient to just allow the mouse
to change the focus.

Thanks,
Melissa