Help moving data from one view to another

I'm developing an application that has several data models that are
related as such: (--> denotes "consists of")

Course --> Topics --> Screens

Screens are based on HTML templates called "building blocks". These
building blocks are identified by an id number.

So, If I want to create a new screen, I have to select which building
block it's based on. So, my new screen view has a button that opens a
popup window containing a thumbnail list of the building blocks. I have
radio buttons setup to identify in the form post which building block I
want.

Once I select the building block, I can make the appropriate new screen
view appear with the id in the appropriate field, however I can only get
the new screen view to open via a redirect which simply opens the new
screen view in the popup window instead of in the main application
window where I opened the popup from in the first place.

How do I get the popup to go away and the new screen view to appear in
the main app window? I know I can do all this via the DOM using
javascript, but I'm trying to utilize/learn the ruby on rails niceties
instead.

Thanks in advance.