bug#7836: 24.0.50; Elisp manual: image slices

[Drew Adams]

Emacs images can be "sliced", meaning they can be composed of "slices".
 
This concept is important for understanding some manipulations of
images, but it is not explained in the manual.  It should be.  What is a
slice? how are slices used? when is it important to know whether an
image is sliced?  And so on.  It's not at all clear what this is all
about.
 
Separately, we need to add an index entry for "image slice" and/or
"slice, image".  Currently (before adding the missing concept
explanation, at least) the target node for this would be `Showing
Images'.
 
In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2011-01-03 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.4) --no-opt --cflags
-Ic:/imagesupport/include'