Comment by mike_hearn

We are doing it. IntelliJ has done it for years. To highlight a string and move from one instance to the next select it, Edit -> Find Usages -> Highlight usages in file then use Next Highlighted Usage.

Other things it can show you via highlighting:

1. Bugs. The online static analysis will highlight code likely to be in error.

2. Dead code. It's rendered in grey.

3. Code that won't execute in this debugger session. Same.

4. Identifiers you chose to temporarily highlight.

5. Mutable vs immutable variables. Also: mutable variables that are never actually mutated.

6. The assertion that failed in the last unit test run.

You can also create your own smart highlighters using semantic search (it's sort of a grep for ASTs).

And a gazillion more. People still using plain programmer text editors are missing out on a lot of features.