We had a FC 20 SE with the small galley window, which was also an escape hatch. Just propped it open for ventilation. If it had the hardware for holding open, it would not open large enough for an escape hatch.
Our new 25 has an operating rear window also designated an escape hatch, and it has the hardware to hold open. But it can still be opened wide enough to climb out, the FC 20 could not due to small size.