The Kendo UI Toolbar widget supports adding attributes to the created DOM elements of items via the various attributes options for items, splitButtons and buttonGroups. I wanted to use this feature for adding custom CSS classes to sub-items of splitButtons. However, this seems to stop the "k-item" and "k-menu-item" classes from being added to the "li" DOM element. The sub-item is no longer clickable. This DOJO demonstrates the behavior.
The problem can be fixed by re-adding those classes manually in addition to the custom CSS class.
I have not tested what happens when custom CSS classes are added to usual items or items in buttonGroups.
When using the Kendo UI Toolbar widget together with the Tooltip widget, the following problem occurs:
In this DOJO, I have created a toolbar that contains a splitButton with several sub-items. The first sub-item has a title attribute that was set using the attributes option. The tooltip was configured to be active for all items with title attributes. As you can see, the active-styling is applied to the first sub-item as soon as the user hovers over it, although the item is not active an has not been clicked or executed in any other way. This does not happen for the other sub-items - they do not have any tooltips.
The wrongly added styles originate from the .k-active class that is added as soon as the tooltip becomes visible.