This is a sketch of Inform 7 semantic highlighting, as I'd like to see it. Run your mouse over the code line below. (It's a real line of code from Heliopause.)

In the popup pane, you'll see standard I6 doc links ( ? ). and source-code links ( < ). I've rendered them in crappy text rather than importing the real arrow icons. Just pretend. Also pretend there's a way to click on them. The UI needs work, obviously.

(This demo requires Javascript, because I didn't try to be clever about the popup code. It will probably also fail on IE6/7.)

• A definition (of rooms) (see ? 6.4. Defining new adjectives):
• non-location <
• The (reversed) containment relation ... one thing to many things (see ? 13.8. The built-in verbs and their meanings):
• non-location room in Journey-One-Beginning
• A phrase ... value (see ? 8.19. Random choices of things):
• a random non-location room in Journey-One-Beginning (description of values)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• A kind of thing (see ? 3.2. Rooms and the map):
• room
• The (reversed) containment relation ... one thing to many things (see ? 13.8. The built-in verbs and their meanings):
• non-location room in Journey-One-Beginning
• A phrase ... value (see ? 8.19. Random choices of things):
• a random non-location room in Journey-One-Beginning (description of values)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• A phrase ... value (see ? 8.19. Random choices of things):
• a random non-location room in Journey-One-Beginning (description of values)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• The (reversed) containment relation ... one thing to many things (see ? 13.8. The built-in verbs and their meanings):
• non-location room in Journey-One-Beginning
• A phrase ... value (see ? 8.19. Random choices of things):
• a random non-location room in Journey-One-Beginning (description of values)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• A room (see ? 3.2. Rooms and the map):
• Journey-One-Beginning <
• The (reversed) containment relation ... one thing to many things (see ? 13.8. The built-in verbs and their meanings):
• non-location room in Journey-One-Beginning
• A phrase ... value (see ? 8.19. Random choices of things):
• a random non-location room in Journey-One-Beginning (description of values)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• A temporary variable (see ? 11.15. Let and temporary variables):
• S (a room variable)
• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)

• A phrase (see ? 11.15. Let and temporary variables):
• let S (a new name) be a random non-location room in Journey-One-Beginning (value)