How to print a form's panel?

Hi,

I'm using Nintex Forms 2013 Standard edition (not Enterprise).

My requiement is to create a "printable" panel with all the controls contained in the form (including Repeating Sections).

I've added a custom Javascript button with the print function, but the print output is blank. 

Has someone here figured out this issue or has a good solution?

Thanks for your help!

Daniel