Need help with Drag and Drop script

I’m using Walter Zorn’s Drag & Drop script on my page:
The script works just fine. But there is a problem when the visitors are trying to print out their design. All “draggble” elements are getting shifted in relation to the rest of the page (try to move “draggble” elements, and then go to Print Preview to see what happens).
The page layout is centered on the screen:
#maincontainer{margin: 0 auto; /Center container on page/}
Drag & Drop script recalculates positions of elements from the Top Left corner.
If I change margin to “0”, than everything prints out just fine, without shifting.
I’d like to keep my page layout centered on the screen and I know nothing about Javascript. How to make necessary changes to the Drag & Drop script to achieve proper page printing?
Drag & Drop script path:
CSS path:

Thanks in advance!