If you select/unselect using Shift-Click, works fine. When you click checkbox on selected row, checkbox turnes to unselected, but row stay selected. It's not only visual effect: this row is returned as selected in query selected.

var gridData = [{ id: "1", name1: "v1" }

, { id: "2", name1: "v2" }

,{ id: "3", name1: "v3"}];

$(document).ready(function () {

$("#grid1").jqGrid({

data: gridData,

datatype: "local",

colModel: [

{ name: "id" },

{ name: "name1" }

],

multiselect: true,

multikey: "shiftKey"

});

});