How do I use dynamic cursor data to zoom in and zoom out of a graph plot?

Through File exchange, I have come across a code that lets me use dynamic data cursors.

dualcursor on; val = dualcursor;

%val = [x1 y1 x2 y2];

Now I can set the xlim using xlim([val(1) val(3)]);

Ideally this should update my plot to the selected values of x-axis values.

However, I think the val = dualcursor picks the values of the dual cursors when it is initally plotted. But for my GUI I need something more dynamic, something that updates the values of val based on x axis values selected.

Please help.