Feature Request Use TimelineEditorWindow without a PlayableDirector

It's great that you can instantiate and run a Timeline graph without a PlayableDirector, allowing a ton of flexibility around use-cases, such as running multiple Timelines simultaneously and blending between them in code. However, the TimelineEditorWindow will only detect that your object is valid for editing and display the assigned timeline if your object has a PlayableDirector component. This has led to a few places in our project where we have GameObjects with a PlayableDirector component that is never actually invoked at runtime, and is used simply to trick the TimelineEditorWindow into opening and displaying our assigned graph.

It would be great if the TimelineEditorWindow didn't look for PlayableDirectors directly, and instead looked for components that implement an interface or two instead that provide the functionality the editor window cares about.