In Hotspot window, it would be nice in hotspot list layer to mention (by an icon, color or other way) which layer contains already some hotspot.
Here is an example.
I have done many times ago a QTVR with several layers. Now, if I want to modifiy it and add a new hotspot, I do not remember how many layers have already been used and I do not know exactly which layer to implement.
This will save some time trying to find the latest or a free layer.