VSAVEAREA                             Introduced: v3.11

  .  Summary

  vsavearea(int <x1>, int <y1>, int <x2>, int <y2>);

  .  Description

  The vsavearea function is used to save a rectangular portion of the
  screen (to be later restored). <x1>,<y1> is the upper left corner of
  the area to save, while <x2>,<y2> is the lower right corner. Charac-
  ters (and their colors) currently on the screen in this rectangle
  are saved in a buffer, and a 'handle' is returned, which must be
  stored and used int he subsequent call to vrstrarea to restore the
  saved area. If not enough memory exists to save the video bytes, a
  value of -1 is returned instead.

  Note that Telix has only a limited amount of space for allocating to
  video buffers of this type. At one time, only about as much area as
  would amount to a full screen should be saved with calls to this
  function.

  It is also very important that for every call to this function,
  there is a subsequent call to vrstrarea. If this is not done, memory
  will become used up until no more is left.

  .  Return Value

  An integer value representing a 'handle' to the saved area.

  .  Example

  int vhandle;

  vhandle = vsavearea(0, 0, 79, 24);  // save the current screen
  myfunc();                           // call a function
                                      // which modifies screen
  vrstrarea(vhandle);                 // restore previous screen