title: Get the key value of the row of whose cusstom button has been clicked
body: <p>I found myself in need of what i guess should be a trivial requirement. i have a jqGrid in which i have added a custom button in each row. now i am able to associate a client side click event with it but i want to know the key value (Id) in my case of the row whose custom button was clicked, so that i can proceed with this id and do whatever i want to do.</p>
  
  <p>My code for jqGrid is as below</p>
  
  <pre><code>jQuery("#JQGrid").jqGrid({
          url: 'http://localhost:55423/JQGrid/JQGridHandler.ashx',
          datatype: "json",
          colNames: ['', 'Id', 'First Name', 'Created Date', 'Member Price', 'Non Member Price', 'Complete', 'customButton'],
          colModel: [
                      { name: '', index: '', width: 20, formatter: "checkbox", formatoptions: { disabled: false} },
                      { name: 'Id', index: 'Id', width: 20, stype: 'text', sortable: true, key: true },
                      { name: 'FirstName', index: 'FirstName', width: 120, stype: 'text', sortable: true },
                      { name: 'CreatedDate', index: 'CreatedDate', width: 120, editable: true, sortable: true, hidden: true, editrules: { edithidden: true} },
                      { name: 'MemberPrice', index: 'MemberPrice', width: 120, editable: true, sortable: true },
                      { name: 'NonMemberPrice', index: 'NonMemberPrice', width: 120, align: "right", editable: true, sortable: true },
                      { name: 'Complete', index: 'Complete', width: 60, align: "right", editable: true, sortable: true },
                      { name: 'customButton', index: 'customButton', width: 60, align: "right" }
                    ],
          rowNum: 10,
          loadonce: true,
          rowList: [10, 20, 30],
          pager: '#jQGridPager',
          sortname: 'Id',
          viewrecords: true,
          sortorder: 'desc',
          caption: "List Event Details",
          gridComplete: function () {
              jQuery(".jqgrow td input", "#JQGrid").click(function () {
                  //alert(options.rowId);
                  alert("Capture this event as required");
              });
          }
      });
  
      jQuery('#JQGrid').jqGrid('navGrid', '#jQGridPager',
                 {
                     edit: true,
                     add: true,
                     del: true,
                     search: true,
                     searchtext: "Search",
                     addtext: "Add",
                     edittext: "Edit",
                     deltext:"Delete"
                 },
          {/*EDIT EVENTS AND PROPERTIES GOES HERE*/ },
          {/*ADD EVENTS AND PROPERTIES GOES HERE*/},
              {/*DELETE EVENTS AND PROPERTIES GOES HERE*/},
          {/*SEARCH EVENTS AND PROPERTIES GOES HERE*/}
   ); 
  </code></pre>
  
  <p>Help or any pointers would be much appreciated.</p>