% append this in the prologue
%
 <font color=#FF0000>/toggle {flag {/fc {0.85 0.65 0.55} D /pc {0.3 1 0.3} D /cc {1 1 1} D /sc {1 0 0} D}
               {/fc {1 0.5 0}        D /pc {0 0 0}     D /cc {1 1 0} D /sc {0 1 1} D} ifelse
               flag not /flag E D } BD</font>
%
% replace this in the body after the rectangle fill
%

 /fc {1 0.5 0} D /pc {0 0 0} D     /cc {1 1 0} D /sc {0 1 1} D
 <font color=#FF0000>/flag true D</font>
 100 -20 0 {layer <font color=#FF0000>toggle</font>} for