EXTJS 4.2 : Copy Selected Gridrows from One grid to another Grid in a new Window on button click

I have a Grid Panel which has a checkcolumn as its selection model and a few rows. I need to have a model where in on a buton click , a new window opens containing a grid wherein all the selected rows from the previous grid appear .

How do I go about achieving this? I have tried loading the rows into a new Store and passing this store to the new Grid. Also a store to store transfer of data seems infeasible ?

Need urgent help people ! Very new to Ext Js.