[ta1243]

I have never looked at the source code for vim, but I have used features that people other than the original developers have created.

I have however looked at the mod_proxy_wstunnel module in apache and edited it to suit my needs. I never expected to do this, I'm not a developer -- certainly not a C++ developer, however running

   sed -i 's/WebSocket/websocket/g' ./modules/proxy/mod_proxy_wstunnel.c

Means it works for my use case. In a world without free software I would not be able to do that simple thing.

Likewise I have changed some custom filters on ffmpeg for my own build. Again that's C, and my C is horrible. I don't need to deal with the somewhat opinionated views of the ffmpeg developers to fold them back upstream - I can just have my 2 or 3 changed files to use them for my purpose.

Just because I don't look at the code for 99% of the software I use, it doesn't mean I don't benefit from it being free software, and for the 1% of cases when I do need to change something, I can. That's freedom, and I'm happy that the GPL ensures my freedom.