cabinet doors may be fashioned either of solid wood or covered by paint, veneer, or laminate in which case they are fashioned of engineered wood. The panels are typically not fastened with glue or nails but rather "float" within the frame to accommodate seasonal expansion or contraction of the wood frame. Solid-door construction. Doors may be fabricated of solid material, either engineered wood (particle board or medium-density fiberboard, but not typically plywood) or solid wood. Engineered wood panels may either be used as slabs or may be shaped to resemble frame-and-panel construction. In either case, engineered wood panels are generally painted, veneered, or laminated. Solid wood panels are typically formed of multiple boards of the selected wood species, jointed together using glue and may either be painted or finished. Solid wood construction offers the possibility of refinishing in case of damage or wear. Decorative panels. Cabinet doors panels can be used decoratively on cabinet sides, where exposed, for a more finished appearance. Glass door construction options. Doors may have glass windows constructed of muntins and mullions holding glass panels (as in exterior windows). Other designs either mimic the divided-light look of muntins and mullions with overlays, or may dispense with them altogether. Cabinets using glass doors sometimes use glass shelves and interior lighting from the top of a cabinet. A glass shelf allows light to reach throughout a cabinet. For a special display effect, the interior rear of a cabinet may be covered with a mirrors to further distribute light. Drawers and trays A functional design objective for cabinet interiors involves maximization of useful space and utility in the context of the kitchen workflow. Drawers and trays in lower cabinets permit access from above and avoid uncomfortable or painful crouching. In face-frame construction, a drawer or tray must clear the face-frame stile and is narrower than the available cabinet interior space. The loss of 2 inches is particularly noticeable and significant for kitchens including multiple narrow [ or less] cabinets. In frameless construction, drawer boxes may be sized nearly to the interior opening of the cabinet providing better use of the available space. However, the same is not true for trays. Even in the case of frameless construction doors and their hinges when open block a portion of the interior cabinet width. Since trays are mounted behind the door, trays are typically significantly narrower than drawers. Special hinges are available