DataTable with DropDownChoice to set rowsPerPage

[Jerry Anders]

I would like to be able to add a dropdown to a DataTable so that a user can 
change the rowsPerPage.  Has anyone done this before?  If not, what is the best 
/ recommended approach?
I tried the following, but I get:

IllegalStateException: Attempt to set model object on null model of component: 
rowsFINALDataTable contacts = NEWDataTable("contacts", columns, 
contactProvider, rowsPerPage) {
    @Override
    PROTECTEDItem newRowItem(String id, INTindex, IModel model) {
        RETURNNEWOddEvenItem(id, index, model);
    }
};

List rows = Arrays._asList_(NEWString[] {"5", "10", "15", "20", "all"});
add(NEWDropDownChoice("rows", rows) {
    @Override
    PROTECTEDBOOLEANwantOnSelectionChangedNotifications() {
        RETURNTRUE;
    }
    @Override
    PROTECTEDVOIDonSelectionChanged(FINALObject newSelection) {
        IF(newSelection == "all") {
            contacts.setRowsPerPage(100000); // use really big number to 
display all
        } ELSE{
            contacts.setRowsPerPage((Integer) newSelection);
        }
    }
});

- JA