Pinta is a free, open source drawing/editing program modeled after Paint.NET. Its goal is to provide users with a simple yet powerful way to draw and manipulate images on Linux, Mac, and Windows.
Features:
Drawing Tools Use easy drawing tools to draw freehand, lines, rectangles, ellipses, and more.
Unlimited Layers Use layers to help separate and group elements of your image for easy editing.
Bi-Tri-Quad-Lingual Use Pinta in your language. Pinta is at least partially translated into over 50 languages.
Full History Don't be afraid to experiment, Pinta tracks your full history so you can always undo.
Adjustments and Effects Pinta includes over 35 adjustments and effects for tweaking your images.
Your Workspace Like docked windows? No problem. Floating windows? No problem. Pinta will even let you mix and match.