Action to change entity screen tab colour on event

Would it be possible to have an action that allowed us to change the colour of an entity screen tab (the label with the name of the screen e.g. Tables, Customer, Reservation, etc)?

We currently use the SabaPOS table resevation setup integrated with a booking form on the website so that when a booking is placed via the website form, it automatically updates the details in SambaPOS. At the moment, we use a message box to inform the cashier a new reservation has been placed, but if she busy (say settling a bill) and clicks OK and then forgets it, the reservation is not checked and acknowledged to the customer. My idea is that if the message box is clicked, an action would then turn the reservation tab red until such time as the reservation had been acknowledged. That way, it would be obvious to the cashier that there was an outstanding reservation for her to attend to.

I believe this request has come up before, but as far as I can see, nothing has ever been done with it.