qvcbar(x0, y0, y1) adds a vertical color bar to the figure between (x0, y0) and (x0, y1), expressed in data coordinates.
If y1>y0, the color bar runs up, else down.
qvcbar(..., w) specifies the width of the color bar in points (default: 5 points). If w is positive, the bar extends to the right of x0, otherwise to the left.
This only works after a preceding qimsc and uses the lookup table (qlut) used by that qimsc.
qvcbar uses qaxshift to create distance between x0 and the color bar.
Positive qaxshift creates space, negative creates overlap.
qvcbar without arguments creates a color bar to the right of the qimsc.
See also qcaxis.