How to open New Window from another window in struts 2.0 without using windows.open

Hello,

I am new to struts 2.0

i had User registration page with a search button on it
If i want to modify User then i have to open the search on new window to select the User and
get id and collection information from DB and display on user page for modification process.

so i am facing some problem in it.

1] How to open the child window from parent window without using windows.open('action name',,,,) or it is necessary to use it.
2] How to render values into that user search table on child window.
3] How to select single use from that table from child window.
4] How to pass selected user id from child window to its parent window on any submit button(on child window).

It's an actual requirement that a new window opens up for this? That seems an unnecessary over-complication.