LazPaint (Version: 4.8) is open source and is a good and very capable alternative to any full featured image or graphics editors. Some of its features are listed below using its menu as a reference and the images attached to this review highlight a few of them.
LazPaint can do multiple undo and redos and paste as and paste as new image. Selections are available as rectangle, ellipse and polygon, these are complemented with curve that can create complex shapes or areas based on initial and end points. Selections can be edited, rotated and there is also the magic wand