Button executing CloseWindow Java Script and raising event on server

Hi All.

Somebody can help me with this:

<b>What i'm needing:</b> an 'END' button on a BSP, when the user click on this button just show an aswer box asking if the user wants to close the windows, in case to click yes close the current window and execute a business logic in the controller.

<b>What i have:</b> a button with the event onClientClick invoking a Java Script function which is showing the answer box and the event onClick which raise the event on the server side. The thing is if the user click on yes then i'm closing the current window and the server event never is triggered. This is not working !!!

Any ideas ? some sample code ?

Thanks in advance.

Armando.