A sliding window assembly (35) including a window frame and at least two glass panes (38, 39). At least one of the glass panes (38, 39) slides within the frame between an open position and a closed position, wherein one of the edges of each pane overlaps to form overlapping edges (42, 43). First and second rails (44, 45) are connected to the overlapping edges (42, 43) and cooperate to form a seal between them in the closed position. Each rail (44, 45) is formed from a metal component (46) and a plastic component (51) that are formed separate from each other and are assembled in nesting connection. The seal in the overlap between the overlapping edges (42, 43) in the closed position of the panes (38, 39) is formed between the plastic components (51) of the first and second rails (44, 45). The metal components (51) of the first and second rails (44, 45) are spaced from contact with each other and extend to overlie outwardly facing surfaces of the first and second panes (38, 39).

Embodiments of windows mainframe components, for example, head/jamb window mainframe components which meet the egress requirements for egress windows are provided herein.

A fenestration unit, such as a window, having an upper sash and a lower sash can be configured to permit separate and independent movement of the upper sash and the lower sash when desired, while restraining the upper sash from movement caused by movement of the lower sash. A fenestration unit having a single movable sash can also be configured to provide securement of the single movable sash against undesired vertical movement.

A window assembly for a vehicle includes a fixed frame having a pair of opposite side frame members, an upper frame member and a lower frame member. A fixed window panel is disposed at a lower portion of the side frame members and at the lower frame member. A movable window panel is movable relative to the fixed window panel and the frame between an opened position and a closed position. Each of the side frame members includes a lower channel for receiving a side perimeter edge region of the fixed window panel and an end region of the lower frame member. An elastomeric seal is overmolded along the lower channel of the side frame member and is configured to receive and seal against (i) the side perimeter edge region of the fixed window panel and (ii) the end region of the lower frame member.