[eluser]vitoco[/eluser]
The first thing that you must understand, it's that the controller works on server side, and it will send an output ( html + js + css ) to the client ( browser ).
So, if you wanna open the result in another window, you have 2 options.
1.- add to the link that calls your controller the attr target="blank_"
2.- load a page with javascript code that opens a new window with the url of the graph.
The difference between server and client side it's fundamental, and how this two interacts with each other it's the base of web development.
Slds