Believe all moving wing was used on the US Navy's F8 Crusader as a means of raising angle of attack at slow speeds, also used on the Helio Courier liason/spotter aircraft of the Viet-Nam era. There has been a regular French visitor to the PFA rally in recent years with a homebuilt staggered unbraced biplane that uses a lower forward fixed wing and the aft top wing with variable incidence for pitch(?) control. It evidently works OK. I believe this was a development of the infamous Pou de Ciel that killed so many people in the'30s that it was banned... Tilt rotors of various kinds have tilted wings in the past, but as some sage noted above it only seems to be helicopters that have actually developed the differential pitch wings mentioned in the original post. Helos win again, I reckon!