Tab的CSS包含如下几个类，从外向里依次：
(1).ajax__tab_header: A container element that wraps all of the tabs at the top of the TabContainer.
(2).ajax__tab_outer:An outer element of a tab,often used to set the left-side background image of the tab.
(3).ajax__tab_inner:An inner element of a tab,often used to set the right-side image of the tab.
(4).ajax__tab_tab:An element of a tab that contains the text content.
(5).ajax__tab_body:A container element that wraps the area where a TabPanel is displayed.
(6).ajax__tab_hover:This is applied to a tab when the mouse is hovering over.
(7).ajax__tab_active:This is applied to a tab when it is the currently selected tab.