So far the SplitButton behaves as a single tab stop component. But the component is created by two buttons, one which triggers a single operation and the arrow which only opens the popup.

The arrow should be part of the Tab sequence so the user can open only the popup without the need to use Alt+Down arrow combination.

The first button rendered in the Splitbutton component always has a type of "button", which is not great if you want the button to automatically submit a form. A "type" input should be added and bound to the first button so that you can set it to "submit".