Required library edition: 
 Required library file: dhtmlxtoolbar.js
adds a two-state button to webbar
 id - id of a two-state button
 
 pos - position of a two-state button
 
 text - text for a two-state button (null for no text)
 
 imgEnabled - image for enabled state (null for no image)
 
 imgDisabled - image for desabled state (null for no image)
 
    toolbar.addButtonTwoState(id, pos, text, imgEnabled, imgDisabled);