Change attribute color/layer per one block only

Hello!

I've read this post:

http://through-the-interface.typepad.com/through_the_interface/2007/02/changing_the_co.html

Everything works fine, but I have one problem.

I just want to change colors for all objects in current model space. But this command also changes attributes/blocks definitions (I mean, any new block which I insert has the color that I specified previous).

Why? Where I have to change the code?