Page 43	Table of Contents	Index	Page 45
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E

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Chapter 6

Overview of Window Facilities

6.1 Introduction

A central notion in organizing user interfaces is allocating screen regions to particular tasks and
recursively subdividing these regions into subregions. The windowing layer of CLIM defines
an extensible framework for constructing, using, and managing such hierarchies of interactive
regions. This framework allows uniform treatment of the following things:

• Window objects like those in X or NeWS.
  
  
• Lightweight gadgets typical of toolkit layers, such as Motif or OpenLook.
  
  
• Structured graphics like output records and an application's presentation objects.
  
  
• Objects that act as Lisp handles for windows or gadgets implemented in a different language
  (such as OpenLook gadgets implemented in C).

From the perspective of most CLIM users, CLIM's windowing layer plays the role of a window
system. However, CLIM will usually use the services of a window system platform to provide
efficient windowing, input, and output facilities. In this specification, such window system
platforms will be referred to as host window systems or as display servers.

The fundamental window abstraction defined by CLIM is called a sheet. A sheet can partic-
ipate in a relationship called a windowing relationship. This relationship is one in which one
sheet called the parent provides space to a number of other sheets called children. Support for
establishing and maintaining this kind of relationship is the essence of what window systems
provide. At any point in time, CLIM allows a sheet to be a child in one relationship called its
youth windowing relationship and a parent in another relationship called its adult windowing
relationship.

Programmers can manipulate unrooted hierarchies of sheets (those without a connection to any
particular display server). However, a sheet hierarchy must be attached to a display server to

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Page 43	Table of Contents	Index	Page 45
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E