CLIM 2 User Guide

Presentation
CLIM associates Lisp objects with their visual representations on the screen. Thus when you
point (with the mouse) to a visual representation on the screen, CLIM can associate what your are
pointing to with a specific Lisp object. The visual representation of the object is called the presentation.
See chapter 8 Presentation types in CLIM for more information.
Viewport
A window stream viewport is the region of the drawing plane that is visible through the window.
You can change the viewport by scrolling or by reshaping the window. The viewport does not
change if the window is covered by another window (that is, the viewport is the region of the
drawing plane that would be visible if the window were stacked on top). When the cursor position
moves out of the viewport, what happens is determined by the end-of-line action or the end-ofpage
action of the window stream.
1.4 Reporting bugs
We are committed to the highest standards of software engineering. Releases of Allegro CL and CLIM are
extensively tested both internally and in the field before wide dissemination. Nevertheless, as with all computer
programs, it is possible that you will find bugs or encounter behavior that you do not expect. In that
event, we will do our utmost to resolve the problem. But, resolving bugs is a cooperative venture, and we
need your help.
Before reporting a bug, please study this document to be sure that what you experienced is indeed a bug.
If the documentation is not clear, this is a bug in the documentation: CLIM may not have done what you
expected, but it may have done what it was supposed to do.
A report that such and such happened is generally of limited value in determining the cause of a problem.
It is very important for us to know what happened before the error occurred: what you typed in, what Allegro
CL typed out. A verbatim log, preferably hard copy, may be needed. If you are able to localize the bug
and reliably duplicate it with a minimal amount of code, it will greatly expedite repairs.
It is much easier to find a bug that is generated when a single isolated function is applied than a bug that
is generated somewhere when an enormous application is loaded. Although we are intimately familiar with
Allegro CL, you are familiar with your application and the context in which the bug was observed. Context
is also important in determining whether the bug is really in Allegro CL or in something that it depends on,
such as the operating system.
To this end, we request that your reports to us of bugs or of suspected bugs include the following information.
If any of the information is missing, it is likely to delay or complicate our response.
• CLIM details. Please tell us the version of CLIM, the machine on which you are running.
• Lisp implementation details. Tell us the implementation of Allegro CL that you are using,
including at least the release number and date of release of Allegro CL, the manufacturer, model
and version of the hardware on which you are running Allegro CL, and the operating system and
its release number. The function excl:dribble-bug will automatically write all the needed
information to a file.
• Information about you. Tell us who you are, where you are and how you can be reached (an
electronic mail address if you are reachable via Internet or uucp, a postal address, and your
telephone number), your Allegro CL license number, and in whose name the license is held.
• A description of the bug. Describe clearly and concisely the behavior that you observe.
14 CLIM 2.2 User Guide