SIZE and LINES describe the area occupied by the Tree-View control, using the control's font to determine the dimensions of a row and column. Additional space is added for the scroll bar (which is hidden when it is not needed). The default height of a Tree-View is 5 lines; the default width is 12 columns. For character-based systems, the size and appearance of the Tree-View control depends on the configuration variables TREE-TAB-SIZE and TREE-ROOT-SPACE.