it can be done with grid.refresh() upon slideDown completion.
complete: function( event, ui ) {
var grid = this;
//$(gridDiv).pqGrid( "groupOption", {"header": true});
$("div.pq-toolbar").hide();
$("span.pq-group-icon").hide();
$("span.pq-group-toggle").hide();
$("div.pq-group-header").hide();
$("<span id='btnHeader'>▼</span>").prependTo("div.pq-slider-icon");
$('span#btnHeader').css( 'cursor', 'pointer' );
$("span#btnHeader").click(function () {
if ( $("div.pq-toolbar").is( ":hidden" ) ) {
//if ($(gridDiv).pqGrid( "groupOption", "header")) {
$("span#btnHeader").html("▲" );
$("div.pq-toolbar").slideDown( "slow" );
//$(gridDiv).pqGrid( "groupOption", {"header": false});
$("div.pq-group-header").slideDown( "slow", function(){
grid.refresh();
});
} else {
$("span#btnHeader").html("▼" );
$("div.pq-toolbar").slideUp("slow");
//$(gridDiv).pqGrid( "groupOption", {"header": true});
$("div.pq-group-header").slideUp( "slow", function(){
grid.refresh();
});
}
});
},