Screenwriting rule 3

This is the third rule that I still use in my novel writing.

Use the dialog to express subtext:

In screenwriting, since you can't write your character was feeling this way or that he thought this way of someone else, you had to have layers of your dialog. This can be simple enough as him saying, "I believe you" with a smirk and a dart of the eyes, or it can be as complex as "You ruined my life" when they are talking their parents because they caught them sneaking out. This works doubly in novels, because you have the added presence of the inner thoughts so you can go further and really expand on the initial comment. Use the dialog, "You ruined my life" as an example. The character could have been sneaking off to see their friend who is leaving the country, or it could be to see their secret boyfriend. But you can play with this in ways because you have the inner thoughts of either the one who got caught, or the one doing the catching depending on the POV.

So I have pointed out three of the major tools that I have learned and developed in screenwriting and implement into my current novel writing.

Have you ever used anything you learned in another field in your novel writing? Research, or job related? I think I know of a specific writer friend who uses her job experience in her writing.