function optpause(opt)
% optpause - Optionally pause and/or update graphics
%
% optpause :: struct {
%    pause :: natural/0 ~'0-nopause, 1-pause, N-timed pause in ms';
%    drawnow :: bool/0  ~'flush graphics before pausing'
% } => void.

ps=getparam(opt,'pause',0);
dn=getparam(opt,'drawnow',1);
if ps, 
	if ps>=10, pause(ps/1000); else pause; end 
elseif dn, drawnow;
end
