Teenagers in the bar! Nothing to do with each other.
Brunette is whistling Alice Cooper's School's Out, but that's the only indication that Junior year (and for Dinah, High School) is over and she's a free spirit. She's actually carrying a thick ledger and a handheld calculator, with which she sets up on a table near the observation window.
Girl's got accounting to do, she can't be thinking about heroing all the time.
Blonde is not whistling. Blonde distinctly doesn't feel like whistling at all. Blonde doesn't feel like doing anything much, except sit in a booth out of the way and hug her knees while feeling useless.
Though the second she sees someone of a Security nature, she's jumping on them.
[A tag of a wee nature: Dinah Lance]