Just to clarify; when the 109 canopy was jettisoned the main canopy was unlocked and flew off, as did the fixed aft portion and radio mast. This photo of Von Werra's 109E shows how the entire cockpit area was opened up (although Von Werra belly landed without releasing the canopy.)
Slightly OT: One of the biggest problems with the Spitfire canopy through most of the B of B is that it could not be jettisoned and had to be slid back by the pilot: if the canopy rails had been bent or damaged the canopy could jam in position