Spatial convolution worker vs beta release

[Cyrille Berger]

Hello,

Since Edward had trouble reproducing Dmitry issue (as mentioned on IRC two 
days ago), here are the steps to reproduce:
* create a blank image
* draw something with the brush paintop
* apply a gaussian blur (I use the default of 10)
* apply a filter level with something link 250-255 as input, and 0-255 as 
output

You should see the noise (it is actually more like a ghost, I am guessing some 
unitialized data). It might also be architecture dependent (I am on 32bits).

-- 
Cyrille Berger