public class Sandbox.UI.KeyFrames

It will be active by default, but you can toggle it with the key-shaped button in the toolbar.

To motion edit, you select a time range of one or more tracks, then tweak the properties that those tracks represent to manipulate track data. You can also cut / copy / paste ranges of time, or save the selection as a separate .movie file.

Movie Maker is a timeline-based editor built into S&box for animating anything in your scene. Keyframe object properties, record gameplay, animate characters with bones and IK, and export finished videos — all without leaving the editor.

You can animate skinned characters directly in the editor using Movie Maker. This tutorial covers: