A Facial Overlay animation CLIP file is used to create the Happy face with the constant smile when sims are happy, inspired, playful, and flirty. This mod replaces the overlay when sims are happy and inspired with the facial overlay used for confident and focused, which is more neutral. The playful and flirty states are left alone, so sims will still have the Happy face when in those states (emotions).
These facial overlays are used when sims are doing various activities like eating, playing guitar, using the computer, socializing with other sims, etc.; so the constant goofy smile when sims are in a good mood no longer exists, unless they are specifically in the playful or flirty mood.
The screenshot simply shows a sim in a happy mood without the smile.
