A window system is constructed by a checking section to check an overlapping state of a plurality of windows displayed on a display, a forming section to form window graphs each showing the positional relation of each window when the windows are seen from another direction such as vertical or horizontal...http://www.google.com.tw/patents/US6163318?utm_source=gb-gplus-share專利 US6163318 - Window displaying system with displaying of set of window graphs showing overlapping state of windows
