Filtering editable-text-dialog-item's

[Thad.Humphries@p0.f716.n109.z1.FidoNet.Org (Thad Humphries)]

I'm new to MCL and am trying to figure out how to filter an editable-text-dialog-item such that a user can only enter a number.  I've tried creating a numbers-only-item class based on editable-text-dialog-item with a view-key-event-handler that will check char and remove it if it isn't a part of a number but I can get anything to work.  Suggestions?