cs5 - How to get an Illustrator script to see the visible size of clipped art instead of the art's orginal size?

When I use an Illustrator script using visible bounds or selection size on clipped art, the script sees the original size of the clipped art as the groups's size instead of its visible (clipped) size. Lets say I have a 150mm x 200mm image and I am using a clipping mask to clip out a 100mm x 100mm part. So now I see a rectangle 100mm x 100mm, then add some other elements on it -- it does not get bigger than 100mm x 100mm. Then I want to work with this size not the, original image's size.

How to implement this in the script to work further with it? I am using Illustrator CS5.