public static interface TreeView.SelectAll
This signal is particularly useful, when you wish to be able to offer the user an option to do some manipulation on the data, when all data is selected. For instance, upon selecting all the rows of the TreeView, in say, an email client, where each row represents an email, an option to mark all emails as read can be made to pop up.
This signal should also be used with much care. The "Principle of Least Surprise" is rather easy to violate by misusing this signal.
boolean onSelectAll(TreeView source)