pp_overlay not covering properly the whole window on smartphones

When the image is display into the lightbox, and then, on click on the “expand image” button, the pp_overlay doesn’t cover the whole window, just the width of the screen, and when you moves the big image to see the rest, the content of the website is shown without the black overlay. Why is that? Is there any solution?

I’ve been looking at the code that is generated by the javascript and sets a fixed width that is the window width, instead of being adapted to the website width that is expanded when the “expand image” button is pressed.

As you can see, I don’t speak in english very well, sorry. And thanks in advance for your help.

http://wordpress.org/plugins/responsive-lightbox/