Hi there, it appears that when using the onClick event to target CSS class names, the target class name must come first if using multiple classes. See this http://webix.com/snippet/f84dcea1 the edit button works but the add button does not, moving the “add” class before the “button” class fixes it.
This is a known limitation.
It will be fixed in one of the next updates. ( most probably Webix 2.2 )