Well, I hate buttons.
I will give feedback to Verant, suggesting that hot buttons should work during spell casting. That's a legacy from old UI days.
I do use a second panel of hot buttons for pet commands when playing my enchanter. When playing other pet classes, I hotkey "/pet attack", "/pet back off" and "/pet report health" and just type the rest as needed.
I just tested the default pet info window with my UI. I had used one element from the pet window in the player window without renaming it. Use the attached player window if you want to use a different pet window.