18.1.1 Properties of Sheets

Sheets have the following properties:

A coordinate system--Provides the ability to refer to locations in a sheet's abstract plane.

A region--Defines an area within a sheet's coordinate system that indicates the area of interest within the plane, that is, a clipping region for output and input. This typically corresponds to the visible region of the sheet on the display.

A parent--A sheet that is the parent in a windowing relationship in which this sheet is a child.

Children--An ordered set of sheets that are each children in a windowing relationship in which this sheet is a parent. The ordering of the set corresponds to the stacking order of the sheets. Not all sheets have children.

A transformation--Determines how points in this sheet's coordinate system are mapped into points in its parents' coordinate system.

An enabled flag--Indicates whether the sheet is currently actively participating in the windowing relationship with its parent and siblings.

An event handler--A procedure invoked when the display server wishes to inform CLIM of external events.

Output state--A set of values used when CLIM causes graphical or textual output to appear on the display. This state is often represented by a medium.

CommonLisp Interface Manager 2.0 User's Guide - 27 Feb 2006