Thanks for getting back to me so quickly.
@guido: is that what you mean? ->
http://iem.at/~zmoelnig/GEM/blur.png
Not really, it looks like [gemframebuffer] has a weird black pixel border all around the edges.
http://img717.imageshack.us/img717/8998/osxfastblur.jpg
This has something to do with osx, please see the patch attached.
http://www.mediafire.com/?tw3jb9o0ac9fq6i
Best,
Guido