ADD TO OTHER FILE:  New Layers are created right over current layer.

http://www.gimp.org/tutorials/Creating_Icons/
http://www.gimpusers.com/tutorials/3d-icons-in-gimp.html

IMPORTANT!  Work with RGB .xcf file, not Indexed!  Do not assign a Colormap
until ready to Save a Copy (and don't save it back to the .xcf).
Work from the intended Palette instead of from the Colormap (this is easier
to use, and shows the color labels too).
Otherwise, you won't be able to use partial opaquity (for anti-aliasing) or
gradients.

N.b.:  THERE IS NO COLORMAP OR INDEX MODE INVOLVED!  We only use a palette
for color consistency.

Work from a color palette for consistency.  <Image>/Dialogs/Palettes
"indexed palette" = "colormap" of an indexed image.  <Image>/Dialogs/Colormap
The Pallette Dialog may be sized larger to see the colors easier.

48x48 pixel images (standard Gnome icon size).

Make 2 views
    8:1 zoom (800%?)
<Image>/View/New View
    1:1 zoom
    <Image>/View/Show Selection off

The "Circle (01)" brush says that it is 3x3, but with Pencil tool, it 
actually draws one pixel.  Unlike the paint brush, the pencil really draws
with 100% opaquity if you set it to 100%.

Draw with
    Pencil, using Opacity (at like 20%) setting to do anti-aliasing.
    Eraser, ditto.   Turn on "Hard Edge" option.
    Airbrush on selected areas (to prevent overspray) for smooth shading
     w/ fuzzy (larger) brush.

Filling
    Use a slight linear gradient for nearly all surface fills.

Gradients
    Use linear gradient for surfaces and curves
    Use radial graiant for round objects

Highlights and Shadows
    Drop shadows.
    gleam or shine in corners.
    lower saturation or value of back corners.

If save to PNG, must Merge (not Flatten) if need transparency.