Abstract: A window having at least one slidable sash which is capable of being pivoted about a central axis. It may include among its features a selectively movable weather-stripping between stiles, a latch between non-rotating and rotating portions of the sash to prevent rotation, double weather-stripping between sash and frame members to optimize integrity of the window against air and water infiltration, and cooperation between the rails and head and still members to prevent the rails from being separated from the frame where the rotatable portion of the sash is in an open, rotated position for cleaning.