addTab(id, text, size, position, row)
Required library edition: 
Required library file: dhtmlxtabbar.js
adds a new tab to Tabbar
- id - the tab id
- text - the tab content
- size - the width(height) of a tab
- position - the tab index , optional
- row - the index of a row, optional [only in PRO version]
See also: removeTab