function request(target, url, param, remainText){
		var opts = $.data(target, 'combobox').options;
		if (url){
			opts.url = url;
		}
		param = $.extend({}, opts.queryParams, param||{});
//		param = param || {};
		
		if (opts.onBeforeLoad.call(target, param) == false) return;

		opts.loader.call(target, param, function(data){
			loadData(target, data, remainText);
		}, function(){
			opts.onLoadError.apply(this, arguments);
		});
	}
request remote data if the url property is setted.