This was working from Alt+N menu but was passing wrong ARegion (alongside wrong mouse coords) to ED_view3d_win_to_3d_int when called from the header menu. Operator context INVOKE_REGION_WIN takes care of this. This also fixes wrong behavior of 'Mesh > Normals > Rotate' when called from the header menu. part of T69019 Reviewers: billreynish, mont29 Maniphest Tasks: T69019 Differential Revision: https://developer.blender.org/D5555