In copy right, we copied source codes illegally or not, which is only thing.
We can refer to source codes which someone produced.
For sale we used someones's source code which is open and created the part of codes ourselves.
We saled software program binary produced by all source codes.
A buyer changed them and brought them to someone.
The above basically succeeds if
1. we suggests open parts is open and someone's.
2. we produced closed parts and suggests that.
And the software would becomes legal.
