Extjs中设置只读的样式问题

view.down('#imageFile').hide();
view.down('#save_button').hide();
view.show();
view.down('form #contentPanel').items.each(function(item, index, length) {
item.setReadOnly(true);
item.getEl().down('.x-form-field').addCls("required");
});
view.down('form #contentPanelOther').items.each(function(item, index, length) {
item.setReadOnly(true);
item.getEl().down('.x-form-field').addCls("required");
});

.required {
background-image: none;
background-color: #ddd;
}