Hi, do you need to be able to activate such hotspots only when clicking within the hotspot's polygonal area? If so, this is not currently supported unfortunately..
I would just like to use them as normal hotspots instead of png's.
I think the simplest most flexible option, would be to use svg's as hotspots. And have different svgs per frame or show/hide different svg groups per frame.
Technically you can do this now using a custom SVG as a hotspot indicator that you can assign on the hotspot form and then duplicating the hotspot (there's a button for that on the Hotspot tab under the list of all hotspots) on each frame and changing the indicator SVG for each required frame as needed. I understand that this doesn't sound optimal... but I believe it should work.