> So I will see if I can find a good tool with a big zoom (I tried in 
> Squeak but got frustrated may be I should retry and hack 
> something...BTW is there in Squeak a graphic editor with a zoom that 
> separates well the pixels? because for icons 16*16 we should work at 
> the pixel level).

Yes, there's FatBitsPaint.  From the class comment (!)  :

        (Form fromUser) morphEdit

For your purposes you might want:

	(Form extent: 16 at 16 depth: 32) morphEdit

You can inspect and/or file-out the result of your handiwork when you
are done.  Just one warning:  all the controls are on the red halo
handle.  Ignore things like the "color" handle and the "repaint" handle.
 In general, though, this looks like a very nice tool for making icons.

-Lex