passing values from gridview in child window to textbox in parent window

hi

I have a page, which contains 2 textboxes. When i click on the first textbox, i have to open a child window (tool), that contains a gridview control with 2 columns (corresponding to the 2 textboxes). When the user clicks on any row in the gridview, it should send back the 2 column values back to the parent window to the corresponding 2 textboxes. Can anyone help me on how do i achieve this?