Never mind.  This behavior and the workaround I needed are already documented in Input.cxx.  Just took me a while to find it....

> Hi.  I have a WordwrapInput window set up to call a callback on WHEN_ENTER_KEY.  This part works.  Unfortunately, the callback also gets called if there is any new text in the WordwrapInput and I go and click on another widget.  Has anyone else had this problem?  Is there a workaround for it?