Ubercart: has an order been paid? Are there any good Ubercart hooks or other API features so I can learn about whether my Ubercart orders have been paid at all?

Basically all I need is a function that would tell me if an order invoice has been paid-in-full or not.
You can use
uc_payment_balance() function to know how much the customer still owes to you.

  uc_payment_balance($order) 


where $order - the order object