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\newblock {\em X Window System Toolkit}.
\newblock Digital Press, 1990.

\bibitem{itsy}
William~R. Hamburgen, Deborah~A. Wallach, Marc~A. Viredaz, Lawrence~S. Brakmo,
  Carl~A. Waldspurger, Joel~F. Bartlett, Timothy Mann, and Keith~I. Farkas.
\newblock {Itsy: Stretching the Bounds of Mobile Computing}.
\newblock {\em IEEE Computer}, 34(4):28--35, April 2001.

\bibitem{layout:1993}
Keith Packard.
\newblock {The LayoutWidget: A TeX Style Constraint Widget Class}.
\newblock {\em The X Resource}, 5, Winter 1993.

\bibitem{render:2001}
Keith Packard.
\newblock {Design and Implementation of the X Rendering Extension}.
\newblock In {\em FREENIX Track, 2001 Usenix Annual Technical Conference},
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\bibitem{pike:draw}
Rob Pike.
\newblock {\em draw - screen graphics}.
\newblock Bell Laboratories, 2000.
\newblock Plan 9 Manual Page Entry.

\bibitem{porterduff:1984}
Thomas Porter and Tom Duff.
\newblock {Compositing Digital Images}.
\newblock {\em Computer Graphics}, 18(3):253--259, July 1984.

\bibitem{x}
Robert~W. Scheifler and James Gettys.
\newblock {\em X Window System}.
\newblock Digital Press, third edition, 1992.

\bibitem{cairo:2003}
Carl Worth and Keith Packard.
\newblock {Xr: Cross-device Rendering for Vector Graphics}.
\newblock In {\em Proceedings of the Ottawa Linux Symposium}, Ottawa, ON, July
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\end{thebibliography}
