Try this out after you add a new layer and adding your white. Click on the smudge tool, go to tool optiond and make sure the box with sample merged is not active.
I just tried it out with a lower version that works for me. When I get a chance this evening at home with V6.1 I will try it again to see if that is the problem you are having.
Also, make sure your color choice is switched from black to white on the forground color. If it is set with black on the forgroung color swatch it will smudge black as you described
Hope this helps you.
-Kevin
hi when i create a new layer on anything and if i add just a white spot and then try to smudge it, it adds black to the outside of what i smudge any idears why its doing it?

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