Pass data from child grid to parent grid

Hello Community! First I have to say this widget is such an awesome tool. Here is what I'm looking to do. I believe its pretty basic. I know how to pass data between the child and parent relationship wtih input fields. Now I would like to accomplish the same thing using grids. I first click a button which opens up a new window containing a grid inside the new window. I want to select single or multiple rows and have the data pass to the grid on the parent page. I am wondering if anybody can help me out with this.

I would like to thank anyone who will take the time to help me in advance.

Check out the 'opener' variable which is filled with a reference to the window which opened the current window.

opener.doTheUpdate(data);