I just posted a hotfix to create thumbnails on the fly (http://www.zope.org/Members/bowerymarc) -- when you use the 'tag' method of Images. It generates JPEG thumbs of the size specified in the tag. You could either use that (so you'd still have access to the original format), or adapt it.
I feel that the term 'Hotfix' isn't really the appropriate label to use for your product; 'Monkey patch' is more approrpiate maybe, as it is not a hotfix. It is not a fix for a serious problem in Zope that cannot wait for the next release, the normal intent of a hotfix, for example. The term 'hotfix' now has contextual meaning, that of a urgent fix for a serious, usualy security related prioblem in Zope. -- Martijn Pieters | Software Engineer mailto:mj@zope.com | Zope Corporation http://www.zope.com/ | Creators of Zope http://www.zope.org/ ---------------------------------------------