since own rB5d9d32fd1fa3 (mirror bbone scaling in editmode) - bbone scaling in posemode was missing immediate updates - bbone scaling in posemode could crash This now properly supports mirroring in posemode as well. note: for bbone scaling, I made both X-Axis-Mirror options (editmode option as well as posemode option) valid. Fixes T64091 Reviewers: brecht Maniphest Tasks: T64091 Differential Revision: https://developer.blender.org/D4851