I am not sure if I understand what you are trying to do, but if you are receiiving the checked nodes, you know that the others are unchecked.

As I know NodesChecked event is triggered every time a checkbox is toggled.

My example: I have tree structure:

-- parent

   -- child1

   -- child2

All elements are checked initially. When I uncheck "child1" NodesChecked returns ["child1"] with IsChecked = true. But when I check it again NodesChecked returns ["parent","child1","child2"] and all of them has IsChecked = true. I need to know for sure which nodes state was changed.

Any updates about this? Is it possible to get actual IsChecked state from NodesChecked event?