jQuery Grid Plugin - jqGrid

Hi,

I was wondering if there's a default callback extension to the setPager function. The section relevant in jqgrid.js is

                $(".ui-pg-selbox", "#" + pgcnt).bind("change", function () {

                    ts.p.page = Math.round(ts.p.rowNum * (ts.p.page - 1) / this.value - 0.5) + 1;

                    ts.p.rowNum = this.value;

                    clearVals("records");

                    populate();

                    return false

                });

but I want to do a callback specifically after the change of the number of rows listed, and NOT on every single call to the URL (which can be easily done using .getPostData()).

Thanks!