when saving a document and it's name contains dots changing of filetype results 
in loss of last part of the filename and replacing of it with extension.

in windows this happens only with oo.org native open/save dialogs, on linux this 
happens always (as there is no other choice)

new document, save as, type name with a dot, then change document type.
for exaple, network.plan-2003-12-14 resu;ts in network.rtf.
usually this is a problem when different version of the same file is needed (for 
mailing to somebody w/o oo.org usually :) )

proposed solution :
a) check last part behind "." against all supported extensions, if found - 
replace, if not - leave as is, attach extension. this could be resources hungry 
(or maybe not), so other possibilities :
b) create an option that controls this behaviour. choices :
1. like in a) - check entered part against extension list;
2. always replace (current behaviour);
3. never replace (as it seems, this is what windows dialog does)

it seems that windows 2000 open/save dialog works fine - it displays filename 
without extension when performing save as and doesn't replace it. oo.org dialog 
also displays without extension, but replaces last part.