in CC3 "Edit Mesh mode", select vertex at right-side of face and push "Mirror Selected" button, vertex at left-side are selected.
But I move vertex at right-side to right, then vertex at left-side move right, too (not oppsite/mirror direction, just same direction).
so these vertexes cannot be edit same time at left-side and right-side.
Is there any way to edit mirroring?