how to supress a window in smartform

how do we supress a window in a smartform when i reach a particular page.my sf has 2 pages defined.first and next.and my output has 12 pages of matter.when i reach a specified page number i dont want a window in my form to b displayed.one thing is that the page number from which i dont want a window is not fixed. it may b 3rd or 4th or any other.

hope to c the reply soon.