Yes, it is a place holder.
The SFCOP's c++ code probably is something like:
char *GetLayoutDescription()
{
  char *result;
  int height;
  int width;
  GetClientSize(&width, &height);
  if ( width <= 640 || height <= 480 )
  {
    result = "640x480";
  }
  else if ( width <= 800 || height <= 600 )
  {
    result = "800x600";
  }
  else if ( width <= 1280 || height <= 0 )
  {
    result = "1280x800";
  }
  else if ( width <= 1366 || height <= 768 )
  {
    result = "1366x768";
  }
  else if ( width <= 1440 || height <= 0 )
  {
    result = "1440x900";
  }
  else if ( width <= 1600 || height <= 900 )
  {
    result = "1600x900";
  }
  else if ( width <= 1920 || height <= 1080 )
  {
    result = "1920x1080";
  }
  else
  {
    sprintf(result, "%dx%d", width, height);
  }
  return result;
}