Hi there 
Feature Idea
A nice feature for Image Occlusion could be “Hide some, ask one”. The idea would be that you can specify, which occlusions should be hidden and which occlusions should be shown as a hint, when being asked about a specific occlusion. This way you could have something like a ‘trailing hint’.
It would be useful for IO cards of tree diagrams, where you could specify, that when being asked about a lower node, the occlusion of the respective higher node is revealed as a hint.
Potential Alternatives
I’ve had a look at Incremental Image Occlusion by @kleinerpirat, which is based on closet by @hengiesel.
Unfortunately, this is not really what i am looking for. The first disadvantage of this approach is, that you cannot rate your answers of the ‘depending’ occlusions separately, since they are one single card. Secondly, IMO you reveal more occlusions than necessary, since there is only the option to incrementally reveal ever more occlusions. Finally, it does not use the native Image Occlusion of Anki.
AFAIK, the feature cannot (at least not easily) be implemented as a JavaScript template of a Anki note type, since the native IO of Anki is implemented with <canvas> and it is not really possible to identify the different image occlusions and modify them after they have been drawn by Anki. However, if someone knows a way of doing this, i would be very happy for suggestions/hints.