jQuery(document).ready(function(){
//"keyup" event handler to reset input fields
$( "#project" ).live('keyup', function(e){
//Improved with keycode checking to prevent extra typing after select
var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
var keyCode = $.ui.keyCode;
if(key != keyCode.ENTER && key != keyCode.LEFT && key != keyCode.RIGHT) {
$('#project-id').val("");
}
});
$( "#project" ).combogrid({
debug:true,
okIcon:true,
autoChoose:true,
colModel: [{'columnName':'id','width':'10','label':'id'},
{'columnName':'name','width':'45','label':'title'},
{'columnName':'author','width':'45','label':'author'}],
url: '/server.php',
//"select item" event handler to set input fields
select: function( event, ui ) {
$( "#project" ).val( ui.item.name );
$( "#project-id" ).val( ui.item.id );
return false;
}
});
});

Type "j" to open the menu. After select an item click "DEL" keyboard button or try typing something else: hidden field will be deleted and a nice icon appears.
"keyup" event handler + "okIcon" option are particularly useful if hidden field is required.