function u=construct(s,sizes_in)
	fg=fig(s); 
	current_value = s.x0;
	ht=uitext('parent',fg,tostring(current_value),'left');

	u=mkunit(s);
	u.process=@proc;
	u.sizes_out = {[1,1]};
	u.dispose = @dispose;
	u.starting = @starting;
	u.stopping = @stopping;

	function starting
		set(fg,'ButtonDownFcn',@btndown);
		set(fg,'WindowButtonMotionFcn',[]); 
	end

	function stopping
		set(fg,'ButtonDownFcn',[]);
		set(fg,'WindowButtonMotionFcn',[]);
	end

	function x=proc, 
		pos=get(ax,'CurrentPoint');
		x=pos(1,1:2)';
	end

	function btndown(a,b), set(fg,'WindowButtonMotionFcn',@nop); end
	function btnup(a,b), set(fg,'WindowButtonMotionFcn',[]); end

	function dispose
		set(fg,'ButtonDownFcn',[]);
		set(fg,'WindowButtonMotionFcn',[]);
	end
end
