How do I for example add support for golang, I know I can setup .go files to be recognized as code. But how do I add the keyword highlighting?

Edit: I figured out how to do the highlighting, now I only need to disable the virtual whitespace, because there are no ; in Go. Is this already supported? Because I read a post from a year ago where it wasn't supported yet?

Virtual whitespace is controlled in 4coder.config, and in the custom code. If you've figured out how to add a language you've looked at the file creation hook. That hooks also sets the virtual whitespace setting. If you use a config file, you can also turn off virtual whitespace there by just setting "enable_code_wrapping = false;"