2.4 Programming Considerations
The major programming considerations are as follows:
- Keyboards are the greatest variable between different manufacturer’s
workstations. If you want your program to be portable, you should be
particularly conservative here.
- Many display systems have limited amounts of off-screen memory. If you
can, you should minimize use of pixmaps and backing store.
- The user should have control of his screen real-estate. Therefore, you
should write your applications to react to window management, rather
than presume control of the entire screen. What you do inside of your
top level window, however, is up to your application.
- Coordinates and sizes in X are actually 16-bit quantities. They
usually are declared as an
int16 (see int16) in
the functions. Values larger than 16 bits can be truncated silently.
Sizes (width and height) are unsigned quantities.
- The types
color (see color),
colormap (see colormap),
cursor (see cursor),
display (see display),
font (see font),
gcontext (see gcontext),
pixmap (see pixmap),
screen (see screen),
window (see window)
are defined solely by a functional interface. Even though they are
treated like structures in this document, it is not specified whether
they are implemented as structures or classes. Although some
interfaces are described as functions, they are not required to be
defined using defun. (It is a requirement that they be
functions as opposed to macros or special forms.)