title: Ajax is not working when using getContext on datatable in Webix
body: <p>I'm setting up a file manager, when right clicking on folder it will popup context menu, before popup am disabling some menu item using ajax. But ajax call is not working when I right clicked on folder which arranged in datatable.</p>
  
  <p>This is my code for popup menu item. Getting error when right clicking on folder which arranged in datatable.</p>
  
  <blockquote>
    <p>webix.js?1.0.0:22356 Uncaught TypeError: Cannot read property 'row' of undefined"</p>
  </blockquote>
  
  <pre><code>    actions: {
              config: function () {
              var t = this.config.templateName;
              return {
              view: "contextmenu",
                      width: 200,
                      padding: 0,
                      autofocus: !1,
                      css: "webix_fmanager_actions",
                      template: function (e, i) {
                      var s = t(e, i);
                      return "&lt;span class='webix_icon fa-" + e.icon + "'&gt;&lt;/span&gt;" + s
                      },
                      data: "actionsData"
              }
              },
                      oninit: function () {
  this.getMenu().attachEvent("onBeforeShow", function (t) { 
  
                      var e = this.getContext();
                      var folderid = e.id;
  
                  $.ajax({
                      url: "&lt;?php echo base_url()?&gt;/Directorylist/directory_activity",
                      type: "POST",
                      datatype: 'json',
                      async: false,
                      data: {'folderid':folderid},
                      success: function (data) { 
                       var json = JSON.parse(data);
                          permission = [];
                          permission = json;
                      },
                  });
  
              if (permission[0] == 1 &amp;&amp; permission[1] == 0 &amp;&amp; permission[2] == 0) {
                      $$(this).disableItem('copy');  
                      $$(this).disableItem('cut');  
                      $$(this).disableItem('paste');  
                      $$(this).disableItem('create');  
                      $$(this).disableItem('remove');  
                      $$(this).disableItem('edit');  
                      $$(this).disableItem('upload');  
                   }  
                      })
                      }
              },
                      actionsData: {
                      config: function () {
                      return [{
                      id: "copy",
                              method: "markCopy",
                              icon: "copy",
                              value: copy
                      }, {
                      id: "cut",
                              method: "markCut",
                              icon: "cut",
                              value: cut
                      }, {
                      id: "paste",
                              method: "pasteFile",
                              icon: "paste",
                              value: paste
                      }, {
                      $template: "Separator"
                      }, {
                      id: "create",
                              method: "createFolder",
                              icon: "folder-o",
                              value: create
                      }, {
                      id: "remove",
                              method: "deleteFile",
                              icon: "times",
                              value: remove
                      }, {
                      id: "edit",
                              method: "editFile",
                              icon: "edit",
                              value: rename
                      }, {
                      id: "upload",
                              method: "uploadFile",
                              icon: "upload",
                              value: upload
                      }]
  
                      }
                      }
  </code></pre>
  
  <p>But when I removed these two lines and given direct value, it works fine.</p>
  
  <pre><code>var e = this.getContext();
  var folderid = e.id;
  </code></pre>
  
  <p>above 2 lines removed and added </p>
  
  <pre><code>var folderid = '1';
  </code></pre>