This is the central class of a JDK 1.1 compatible GIF encoder that, AFAIK,
supports more features of the extended GIF spec than any other Java open
source encoder.
Instances of this Gif89Frame subclass are constructed from bitmaps in the
form of color-index pixels, which accords with a GIF's native palettized
color model.
Setting this option determines (in a cooperative GIF-viewer) what will be
done with this frame's display area before the subsequent frame is
displayed.