Rails - Apr 2009 - how to get acts_as_versioned able to delete only selected version

Hello everyone

i''m working on uploading file by using attachment_fu and
acts_as_versioned


so the problem is i can''t delete only selected version


for example ;

i have file a.txt  and this file have 5 version each version is
viewable ( that mean you can view version 1 , version 2 , version
3 .............. )

a.txt ( version1 )
a.txt ( version2)
a.txt ( version3 )
a.txt ( version 4)
a.txt (version 5 )  <<<<< latest version

and i would like to delete ONLY version 3  so the result after delete
should be like this

a.txt ( version 1)
a.txt ( version 2 )
a.txt ( version 4)
a.txt (version 5 )  <<<<< latest version

and if user choose delete version 5 , the result after delete should
be like this

a.txt  (version 1)
a.txt ( version 2)
a.txt (version 4)  <<<<<<<<< latest version

any suggestion ?

ps. sorry about my english