This variable controls the number of screen columns between the left edge of the Tree-View control and the root level text. TREE_ROOT_SPACE is used only with the LINES-AT-ROOT property. If LINES-AT-ROOT is not specified, the root level item text will be displayed starting at the leftmost screen column inside the tree-view control.
For example, if TREE_ROOT_SPACE is set to 5, there will be 5 screen columns before the text of each root level item. The screen column where the root level line will be drawn is determined by this formula:
root level-line = (TREE_ROOT_SPACE - 1)/2 + 1
Taking off from the previous example, if TREE_ROOT_SPACE=5, the root level line will be drawn in screen column 3, counting from the left edge of the Tree-View control.
This has the effect of centering the vertical root level line in the space between the left edge of the Tree-View control and the last root level text.
The "+" or "-" button is displayed in the column to the right of this vertical line if the TREE_ROOT_SPACE is set to a value greater than or equal to 2. If the TREE_ROOT_SPACE is set to 1, the "+" or "-" button appears in the first screen column of the Tree-View control. The default value of TREE_ROOT_SPACE is 2.