How to retrieve UI element properties that Accessibility API does not provide ?

I have a cocoa application running and there is a NSButton on it. From another process, I can get some properties of that Button via Accessibility APIs (i.e. by AXUIElement). Obviously, only limited properties are exposed, I can not get properties like "buttonType", "KeyEquivelant" through this way.

So, my question is, Is there any fundamental APIs on Mac that can retrieve properties of a UI element, particularly in an cross-process way.