Stipple is a kind of pixle-toggling using a bitmap. Gnus uses this, for example, to insert a wonderful Gnus into the splash screen.
To illustrate this, the following code fragment creates a Face with a stipple consisting of a 2x2 bitmap. The top right and the bottom left corner are set. Tiling this bitmap gives a chess-board bitmap.
(make-face 'foo) (set-face-stipple 'foo (list 2 2 (string 1 2)))
The following the inserts the string foobar into the buffer and adds the stipple to the first three characters. Evaluate this in a buffer without font-lock (as font-lock removes all non-font-lock TextProperties immediately).
(let ((str "foobar")) (put-text-property 0 3 'face 'foo str) (insert str))