Name
GrNewPixmap -- Allocate a new pixmap
Synopsis
GR_WINDOW_ID GrNewPixmap (
  GR_SIZE width,
  GR_SIZE height,
  void *  addr
);
    Parameters
- width, height
- The dimension of the new pixmap. 
- addr
- Reserved for future use to support shared memory.
              For now, use zero or NULL. 
Return Value
Returns the window ID of the new pixmap.