When there are no fully selected bones, use the normal of bones which only have the root/tip selected as a fallback. Without this, the extrude gizmo isn't very useful since extrude is often used with only the tip selected.
When there are no fully selected bones, use the normal of bones which only have the root/tip selected as a fallback. Without this, the extrude gizmo isn't very useful since extrude is often used with only the tip selected.