Two of my addons (VSE Quick Functions, and another I have not released yet) rely on the scene_update_post handler, which has been removed along with scene_update_pre
(See the first ‘Open Topic’ at: https://developer.blender.org/T47811 ).
I don’t think this functionality can be properly replicated with a modal operator. I have tried in the past and run into reliability issues, and as far as I know, this isn’t what modal operators are supposed to be used for either. So what am I supposed to use for this now?
I get that it isn’t working the way it was intended right now, but without an effective alternative, removing it entirely is not the solution…