Why does the "Live Unwrap" option exist twice?

This is about Blender 2.71.
There is one “Live Unwrap” in the UV / Image Editor and a second one in the Edit Mode under Options -> Mesh Options. This Edit-Mode-Live-Unwrap works as expected (great tool by the way) but the UV-Editor-Live-Unwrap doesn’t seem to do anything. Am I missing something?



They are two different things
Read their tooltips

If you don’t see anything happening with the second one then I expect you haven’t pinned any vertices