Please describe the problem:
If I want to apply filter(spread for example, but it's not important which filter, because it's works the same with all filters) for  3 channels RED, GREEN, BLUE I see in preview window this:
http://img146.imageshack.us/img146/9692/screen1z.jpg
and after pressing OK the result will be as expected:
http://img512.imageshack.us/img512/3345/screen2k.jpg
Now If I will do the same only for 2 channels, RED and BLUE, I will see in preview window the result of applying for all channels, and NOT for only 2:
http://img189.imageshack.us/img189/9343/screen3ruc.jpg
And this is the expected result (pink areas, very ugly, but this is just example):
http://img257.imageshack.us/img257/8379/screen4q.jpg



Steps to reproduce:
1.chose not all channels 
2.Try to apply any kind of filter 



Actual results:
You will see the diffrence between expected result and what shown in the preview window.


Expected results:
It will be nice to see expected result

Does this happen every time?
YES

Other information: