Allow annotation of code and regular text files, similar to PDF

This feature would allow one to drop in a text file (or any code file) and have it render in another view just like PDF, allowing the user to add annotations or just view the file. This would be very useful to me when referencing code blocks from projects, or bringing over plain text data. The code blocks are useful, but not as useful as having an entire code file with context to refer back to.

I got the exact same idea few days ago. Could be very useful during some kind of code review to annotate the code and to reference some link to another part of the code (ref to file + line number ?)