our parent class Ext.grid.GridPanel sets 'tbar: null' and Ext.applyIf() will only apply our property if it is undefined, so switch to Ext.apply() it is safe to use Ext.apply() because none of these classes is further extended, so we don't have to worry that might me might override a toolbar set further down by a child class this fixes allows the panel to display its top toolbar with add/edit buttons