How to get page header (fixed page header) in pagebeforeshow event?

How to get page header (fixed page header) in pagebeforeshow event?

If the header is not fixed, in pagebeforeshow $('div[data-role=header]', $.mobile.activePage) could get to page header. When in fixed header, before transition happen, the header is not available in pagebeforeshow  event. Looks like it is removed before real transition happens. How to get page header (fixed page header) in pagebeforeshow event?

Thanks!

Jerry