> can't we figure out the final pass index taking left/right into account later?

yes we can, so we recalculate the multindex and pass every time we draw in the screen. I was trying to avoid that, but I don't think it's a performance problem.

I will look at that. It will likely fix the problem of lack of update when you open a new image (given that we are getting the right pass/index only after selecting a view from the UI)