I have an idea for you, here is what I would do.
Since your listview contains a collection of all open windows already, why not also have your listview store each window's handle in the item tag like so.
ListView1.Items(i).Tag = 'code to get the handle here, i is the index
now, when a user clicks on the listview item, retrieve that item's tag(the corresponding window handle), and then put the value in whPoint.
I believe this is what you wanted to know but maybe that is not where you were having the trouble? let me know.
good luck