Hi David,
Thanks for your request. This has been already logged as a feature request for GWD team.
I don't know if this helps, but some of the work-arounds I can think of is to create an empty div, add animation inside the div.
You can copy/paste the nested div. Or, another is to create animation for a layer, then create a group from Right-click menu.This will encapsulate the animation in a group.
You can copy/paste the group. I don't know if this will benefit to your scenario, but just an idea.
Thanks,
Mariko (GWD team)