Expands the specified node so it corresponds to the expanded attribute in
the configuration.
Parameters: parent - node to check if it should be expanded or not.
Returns the tree node that is intended for a drop action. If this method
is called during a non-drag-and-drop invocation there is no guarantee
what it will return.
the folder tree node that is targeted for the drop action; nullotherwise.
Returns the tree node that was selected before a drag and drop was
initiated. If this method is called during a non-drag-and-drop invocation
there is no guarantee what it will return.
the folder that is being dragged; null if it wasnt initiated inthis component.