13.7.7 clear-rectangle deprecated

The function gp:clear-rectangle is deprecated. This is because it ignores the graphics state, which means it does not work properly with other drawings. In particular it does not work properly in the display-callback of capi:output-pane .

Instead call:

(gp:draw-rectangle ... :filled t :foreground color

                   :compositing-mode :copy :shape-mode :plain)

LispWorks Release Notes and Installation Guide - 23 Dec 2011