This setting controls how cascading and undetermined nodes are applied.
If 'up' is in the string - cascading up is enabled, if 'down' is in the string - cascading down is enabled, if 'undetermined' is in the string - undetermined nodes will be used.
If three_state is set to true this setting is automatically set to 'up+down+undetermined'. Defaults to ''.
a boolean indicating if the selected style of a node should be kept, or removed. Defaults to true.
a boolean indicating if checkboxes should cascade down and have an undetermined state. Defaults to true.
a boolean indicating if checkboxes should be visible (can be changed at a later time using show_checkboxes() and hide_checkboxes). Defaults to true.
a boolean indicating if clicking anywhere on the node should act as clicking on the checkbox. Defaults to true.