Required library edition:
Required library file: dhtmlxtoolbar.js
adds a listed option to a select button
parentId - id of a select button
optionId - id of a listed option
pos - position of a listed option
type - type of a listed option (button|separator)
text - text for a listed option
img - image for a listed option
toolbar.addListOption(parentId, optionId, pos, type, text, img);