the same order, without swapping them around, so that they will continue to slide easily. This type of mounting, where the panels overlap by a stile-width when closed, is called hiki-chigai (). Hiki-chigai came to be used in minka (commoners' homes) in the mid-Edo Period (c. 1700s). Katabiki shoji () are single panels sliding in a single groove. They slide on rails mounted on a solid wall, and when open partly or fully overlap the wall. They are used for smaller windows in opaque walls; this is common in chashitsu (see image). Small windows and katabiki mounting were used in minka until the mid-Edo period, but were then replaced by larger openings with sliding panels. Full-height shoji set up so that they can be slid in front of an opaque wall are not common in modern Japan. Washi-on-frame panels can also be used to diffuse an artificial light source; in Japanese lampshades, this use is both common and traditional in Japan. Less traditionally, hiki () shoji (sliding panels) can be hung on rollers, which run on metal rails mounted on the side of the kamoi. This avoids fit problems caused by humidity-related changes in the dimensions of wood. Such rail-mount shoji require an anti-sway pin, but may otherwise have a smooth, unobstructed threshold. Such shoji are also fairly easy to remove. Shoji may also be installed as pocket doors between rooms, called hikikomi () shoji. This is a historical practice, but it is no longer common in Japan, though it is sometimes used in western-style homes. Shoji in Europe are commonly suspended on panel-blind track, by 'touch-and-close' fastener such as Velcro. No bottom channel is required or used – panels are typically 16–17 mm thick made from Obeche timber rather than traditional conifer wood. This method has the advantage of being less likely to break but can move in strong draughts. Other suspension methods are sometimes used. Kake-shōji (hanging shoji) are mostly used in traditionally rustic chashitsu (tea rooms). They are commonly hung over small windows in opaque walls of mud plaster; they hang from bent-nail hooks, one on either side of the top of the window, and the topmost frame member is extended into two horizontal projections that rest in the hooks (see photo above). Like katabiki shoji, kake shoji may be placed on the inside or the outside of the wall, depending on what suits the window. Hiraki