Checkboxes
The TreeView allows the user to select nodes by using node checkboxes.
To render a checkbox next to each item, set the checkboxes property of the TreeView to true. A TreeView item is checked when the checked field of that item is set to true. Each TreeView item is in indeterminate state when its checkIndeterminate field is set to true.
Instead of checked and checkIndeterminate, you can implement your own fields by setting the checkField and checkIndeterminateField properties to the names of the custom fields.
