[Antialiaising went messy]

I don't know what I'm doing wrong, but when I set the brush or line tool to Antialiaising on then draw, then fill it in with the bucket tool, often the near the outline there are real light colored (almost white) pixels, like this, This is hard to ignore. Does anyone know how to fix this? I see most art doesn't have this impurity... Tanks in advance.

[Gradient filler?]

Okay, thanks .

[Gradient filler?]

Does anyone know if there's such thing as a gradient filler for paint.NET? Ya'know, like a paint bucket tool that fills an area with gradient, unlike a backround tool? I need something like that...