Called every frame unless the panel is not visible (Panel:IsVisible). Similar to PANEL:Think, but can be disabled by Panel:SetAnimationEnabled as explained below.

If you are overriding this, you must call Panel:AnimationThinkInternal every frame, else animations will cease to work.

If you want to "disable" this hook with Panel:SetAnimationEnabled, you must call it after defining this hook. Once disabled, a custom hook will not be re-enabled by Panel:SetAnimationEnabled again - the hook will have to be re-defined.