This script displays a dialog box for pre-composing one or more layers (like the built-in Pre-compose dialog box), but adds the ability to trim the pre-comp to the selected layer’s duration, with optional trim handles.

Creates a new Adjustment Layer and trim it to the range of the selected layers.

Trim to Layer Above will trim the layers that are selected to be the same length as the layer above it. Trim to Layer Below, well, trims the layer below the selected layer.