[Bf-cycles] problem compositing raytraced DOF

[Bassam Kurdali]

When compositing raytraced DOF I'm noticing that alpha is not where I
expect it to be, i.e. there is some transparency in opaque part,
resulting in light leaks, at least that's what I think is going on.

Hi all, I'm not sure if this is:
a- a bug
b- not enough samples issue
c- just not possible to comp alpha blurs this way :)

so I'm posting a .blend here:
http://www.pasteall.org/blend/27271

If the answer is C am I correct in assuming I can still render in render
layers, and use the add node to add light in one layer on specific
objects? 

so instead of : 

background has light A

foreground has light A + light B

alpha over foreground to background

I'd do:

background + foreground has light B

foreground has light A

add foreground to background + foreground...

cheers,
Bassam