% (you can specify all those properties at the same time as you create the
% uicontrol)
my_third_button = uicontrol( ...
'Style','pushbutton', ...
'Units','normalized', ...
'Position',[0.65 0.05 0.3 0.15], ...
'String','Randomize', ...
'Callback',{@randomize,plot_point_handle}); % pass the line handle as an additional argument to the Callback function
% Define the Callback:
function randomize(~,~,h)
% h is the handle to the plotted line (a.k.a. "plot_point_handle" in the calling workspace)
new_point = randn(2,1);
set(h,'XData',new_point(1),'YData',new_point(2));
end
