Mask and Clip behavior

Hello all,

I'm currently experimenting with Clip and Mask.

I ran a little test case to figure how maskUnits, maskContentUnits and
clipPathUnits work.
You can see it here : http://jsfiddle.net/JeremiePat/JdQd4/

Most of the time, when I'm using the value "objectBoundingBox" for those
attributes, my tests (on the left side) does not follow my expectations (on
the right side) (at least with Firefox, Chrome and Opera).
I read the spec carefully and I wonder if I made false expectations, if I
made mistake in my code or if it's just all those browsers that are buggy.

Could you tell me if what I expect is right (and in that case, I'm ready to
report bugs to browser vendors) or if I missed something in the spec (and
in that case, I wish to discuss how to clarify the spec)?

Thank you all

Best regards
-- 
Jeremie
.............................
Web : http://jeremie.patonnier.net
Twitter : @JeremiePat <http://twitter.com/JeremiePat>