code: function(record, columnHeader) {
          var me = this,
              grid = me.editingPlugin.grid,
              store = grid.store,
              view = grid.getView(),
              context = me.context = Ext.apply(me.editingPlugin.context, {
                  view: view,
                  store: store
              });
  
          if (!me.rendered) {
              me.render(view.el);
          }
          // make sure our row is selected before editing
          context.grid.getSelectionModel().select(record);
  
          // Reload the record data
          me.loadRecord(record);
  
          if (!me.isVisible()) {
              me.show();
          }
          me.reposition({
              callback: this.focusContextCell
          });
      }
docs: Start editing the specified grid at the specified position.
  @param {Ext.data.Model} record The Store data record which backs the row to be edited.
  @param {Ext.data.Model} columnHeader The Column object defining the column to be edited.