The scrolling functionality looks great now. Indeed setting the djvu-continuous to t provides the functionality that I requested/proposed.
Regarding the annotation features, I have implemented more in djvu2.el than just highlighting rectangles. It also shows free text, line and arrow annotations. I think those things can not be implemented via `djvu-image-rect`. The djvu2.el page contains a
demo screencast. Just to remind you, djvu2.el also implements djvu-occur and imenu functionality.
Regarding tooltips based on pixel coordinates, this can be achieved (as it has been done in pdf-tools) via the `:map` and `:pointer` keywords in the
image descriptor. However instead of implementing this separately, I think it would be great if as much as possible of the pdf-tools code could be reused (I mean that djvu and pdf share as much code as possible for similar functionality). Although it would be great if it got implemented, so that Emacs also becomes the best document reader, for me personally the invested time would not be worth the gain (Although I might have a look at it some time as some kind of exercise. djvu2.el for me was also just an exercise/study).