It has been possible to save a custom easing in the easing functions menu: you create your own and Add it to List (look at my screenshot)
This 'Add to List' option creates a custom item but it stays available only inside that very document. If you open a new document and want to use your custom function created in a previous doc, it isn't there anymore.
Here comes the Feature Request:
A kind of 'MySnippets-list' for saving fav JS functions in a library within Hype on the program level, so that it will be available in all hype documents, new or previously created.
Similar thoughts and requests on snippets libs were already heard on this forum, e.g.: