The question that remains for me is how to do this. Personally,
I don't like applications which tack on anything to the file name
after I've typed it. If I typed "foo" I want "foo", nothing else.
The Gimp, and other helpful applications, will (during save time,
in the dialog) append the proper suffix to your string ("foo")
_if_ you explicitly select a file type from the drop down list.
I would be in favor of having AbiWord do similar.
The basic concept is that whatever's in that entry box should
always be the file name, nothing more, nothing less--the program
shouldn't corrupt that string after "OK" but before fopen().
-- Shaw Terwilliger