0bc95b7b40
Main motivation is from T54314 where there was no way to read from a Viewer image datablock after setting another viewer node active. Part of the problem was addressed in rB16d329da284c (where handlers for the compositing background job were added so that you can act after the compositor has run), however there was still the remaining issue that setting another viewer node active would not properly tag the node NODE_DO_OUTPUT. This forced users into a complicated workaround (using switch nodes feeding into a single viewer node). Now handle NODE_DO_OUTPUT properly in RNA, too, and do proper updates so that behavior from RNA matches that of the Node Editor when setting a viewer node active. ref T54314. Reviewed By: JacquesLucke Maniphest Tasks: T54314 Differential Revision: https://developer.blender.org/D15203