To make text-based icons (24x24):

1. Make a new image in GIMP, wide and 24 pixels tall.
2. Fill with a background color, e.g. #004080.
3. Add text in capitals, white, Trubuchet MS bold, 19 pixels.
   This leaves ten pixels spare vertical space.
4. Move the text to allow five pixels top, left and bottom margins.
5. Crop the image to leave five pixels right margin.
6. Lighten the top and left margins (two pixels).
7. Darken the bottom and right margins (two pixels).

