oWin:upDate() -> < void >
------------------------------------------------------------------------------


 DESCRIPTION:

  The ::Update() method will call the refresh() method of every
  control that is attached to the window, and that has the instance variable
  ::lUpdate set to TRUE. This allows you to update selected controls 
  on a particular window with just one call. 
  
  The ::lUpdate Flag is normally set with the keyword UPDATE when
  you (RE)DEFINE a control.