The Oberon OS is a unequaled pinnacle of user interface design, IMHO.
(In addition to the Oberon language, which is great (in context), and the internal organization of the Project Oberon OS in an education in itself. (Prof Wirth has kindly made the book into PDFs for distribution, available here: http://www.projectoberon.com/ This book is soooo good for computer system design).)
(In addition to the Oberon language, which is great (in context), and the internal organization of the Project Oberon OS in an education in itself. (Prof Wirth has kindly made the book into PDFs for distribution, available here: http://www.projectoberon.com/ This book is soooo good for computer system design).)