SET(CROSS_WINDOW_BOUNDS)
  Determines the effect of CURSOR_VERTICAL on the cursor.  When
  CROSS_WINDOW_BOUNDS is set to ON, the CURSOR_VERTICAL built-in may cause
  the cursor to pass over window boundaries on the screen.  When
  CROSS_WINDOW_BOUNDS is set to OFF, the CURSOR_VERTICAL built-in causes the
  cursor to move only within one window and to obey scrolling regions.
  Syntax
     SET (CROSS_WINDOW_BOUNDS, {OFF | ON})
  Parameters
     OFF        Causes the CURSOR_VERTICAL built-in to move the cursor only
                within one window.
     ON         Allows the CURSOR_VERTICAL built-in to move the cursor over
                window boundaries.  This is the default setting.
  Example
     SET (CROSS_WINDOW_BOUNDS, OFF);
  Prevents the CURSOR_VERTICAL built-in from moving the cursor out of the
  current window.  Instead, text in the window scrolls if the cursor moves
  into a scrolling region.
  Related Topics
     CURSOR_VERTICAL