backdrop issue with multiple modal
$(document).on('show.bs.modal', '.modal', function (event) {
var zIndex = 1040 + (10 * $('.modal:visible').length);
$(this).css('z-index', zIndex);
setTimeout(function() {
$('.modal-backdrop').not('.modal-stack').css('z-index', zIndex - 1).addClass('modal-stack');
}, 0);
});