Abstract: A window construction applies to vertically or horizontally hung windows including horizontally sliding windows, to conventional double-hung windows wherein one or both sashes are movable, and to odd-shaped windows (hexagons, octagons, or the like). The outer window framework comprises lineal sections providing a header, a sill, and a pair of jambs, joined by formed corner sections of complementary cross-sectional configuration to achieve water-tight corner joints and a water-tight window. The outer framework incorporates flanges for mounting the complete window in a window aperture of a building or vehicle, and channels for receiving an inner framework of sashes and/or vents, and providing a peripheral seal for the same. She internal sashes may be single or multiple frames holding glass or comparable transparent or translucent panes.