What do you mean back of the smiley looks white in dark background?
Format files of Smilies

oh ok.. I thought you meant just viewing it normally, that you see a black background but I see you mean when you insert a smiley onto a black background THEN you see the white outline.
I have a suggestion about the smilies. For example:
Back of the smiley looks white in dark background. I'm wondering if there is any solution for this; what about saving their files in .tga or .png?