Suggestion: Allow Code Highlighting per file

I have my screen split into two. On the left side are the file/files I am writing tests to cover. On the right are the tests themselves.

I find it difficult to write code when code highlighting is on but I need to see highlighting on the left side to know what to write.

How about a toggle on the code file form itself to override the global setting? (Maybe use that wasted space in the bottom right corner)