the basic concept of Efl.Ui.Tab_Pager is similar to elm_toolbar.
user can attach Efl.Ui.Tab_Bar to the tab_pager.
user can create an Efl.Ui.Tab_Page to add tab label, tab icon and set the content of the page.
user can pack Efl.Ui.Tab_Page into tab_pager.
The tab and page match one to one.
user can controls tab and page through tab_pager.