of Hypertext and Graphical User Interfaces

Correspondence with Alan Blackwell

6 May 2005, Alan Blackwell

Subject: Vision and Reality, old papers, and Kay
Date: Fri, 06 May 2005 14:19:57 +0100

Dear Matthias,


Third, you may be able to solve a puzzle for me. Alan Kay's talk in the book "History of Programming Languages" briefly mentions the relationship between overlapping windows and the term "desktop". My impression is that he (or someone else at PARC) just looked at those clipping boundaries one day and said "hey - they look like pieces of paper on a desk". This is probably lost in the mist of time, but Kay says in his talk that he summarises the history of overlapping windows in [Kay 1989]. Unfortunately the bibliography doesn't include any reference from 1989. It occurred to me that you might know what he was referring to - do you?

Best regards,

7 May 2005, Matthias Müller-Prove

Hi Alan,


Well, let’s see. I looked up [Kay 96] to find his comments on overlapping windows, the desktop, and "1989".

p 531: ... first overlapping windows started to appear ...

p 537: Overlapping windows were the first project tackled ...

pp 537: The first practical windows in Smalltalk used the GRAIL conventions of sensitive corners for moving, resizing, cloning, and closing. Window scheduling used a simple "loopless" control scheme that threaded all the windows together.

Neither an evidence for "desktop", nor "1989". Is there even "paper" used in the chapter? I have to confess that I just skimmed over the pages. But as long as you do not show me the exact location I am not even surprised.

Overlapping windows are a very obvious feature of Smalltalk. Much effort was spent to improve performance and interaction with the windows. In my opinion mostly for two reasons: 1) limited real screen estate and 2) to reduce modes in the user interface. Do you know [Tesler 81]

p90: "If you stop any program and start another, data displayed by the first program is probably erased from the screen and irretrievably lost from view. In general "running a program" in most systems puts you into a mode where the facilities of other programs are unavailable to you. Dan Swinehart calls this the dilemma of preemption[...]"

Overlapping windows are a way to overcome this dilemma. All is visible – partly. Mode switching cost no mental effort at all

p96: "The various "windows" look and behave like overlapping sheets of paper."

In my opinion Kay’s Learning Research Group at Xerox Parc (LRG) was not aiming at an coherent system over all. Smalltalk at Xerox Parc was a beautiful environment for experimenting with new concepts. Playing with math "for children of all ages".

Once Xerox decided to build a commercial system - the Xerox Star - coherence and familiarity with the real business world became very important. The desktop metaphor as a whole was developed since 1977. It was then called "the physical office metaphor" [Smith et al. 82], [Newman/Mott 82].

Regarding the reference to 1989. There is an article [Johnson et al. 89] which contains sections on windows and the desktop metaphor.

p 13: Star, unlike all conventional systems and many window- and mouse-based ones, uses an analogy with real offices to make the system easy to learn. This analogy id called "the Desktop metaphor."

This article is the best to my knowledge, that describes all aspects of the Xerox Star.

Hope this helps. Let me know if I should try to be more specific and accurate on certain points. I can provide PDF or paper copies of the cited references.

All the best