[This is preliminary documentation and is subject to change.]
The contents of the original Pane is placed in one of the new panes, and the other Pane remains empty. The orientation of the two panes and which Pane will be empty is determined by the supplied PaneType.
The original Pane must be Splittable, otherwise an exception is thrown. New names are assigned automatically for the new panes. The original Pane still exists and becomes the parent Pane of the two new Panes.