Abstract: A self-contained closure and closure frame assembly are easily mounted in the cabin of a boat, requiring minimal disturbance of the boat structures. The closure requires a minimum of space during movement from a closed to a fully open position, the closure first being moved outwardly generally parallel to the cabin, by pivoted levers, to an initial open position, and then slid to a fully open position. Slide tracks are provided in the closure itself, and they cooperate with slide mechanisms pivotally connected to the closure frame. A series of levers and interlock elements insures proper and secure pivotal movement of the slide mechanisms between closed and initial opening positions, and does not allow sliding movement of the closure until it is substantially in the initial open position. Sliding movement is positively guided to substantially prevent skewing in any plane as the closure is slid open with respect to the frame.