Drag a transition segment to move it or curve it

When editing a transition it would be nice when click-dragging a segment to move it or curve it instead of only adding a point, the behaviour would be:

• clicking will add a point

• click dragging up/down to curve the segment

• click dragging left/right to move the two extremities of the segment (of course you then need to handle what happens if we come near another point, maybe limit the movement up to next/previous point, this would be simple enough bu not too limiting ?)