despite being a good paint editor for Windows, it is unfortunately not open source or source released (I thought it was as well):
However, citing issues with the open source code being plagiarised by others that had rebranded the software as their own and bundled user content without their permission, the availability of the source code was restricted
In November 2009, the software was made proprietary, restricting the sale or creation of derivative works of the software.
great pixel art