{Development of TeXShop\Dash the past and the future} {Yusuke Terada} {TeXShop is a widely-used open source \TeX\ editor and previewer for \MacOSX. TeXShop is developed by Richard Koch, emeritus professor of mathematics at the University of Oregon, and many other worldwide contributors including me. Now it is localized for as many as 10 languages. While it has already sufficient functions for editing \TeX\ documents, TeXShop is still being updated. In this presentation, I will give an outline of the design concept of TeXShop and some new features that have been added recently, especially for editing Japanese documents. In addition, I will show a vision of TeXShop for the future. }