GimpTile
typedef struct {
  guint         ewidth;     /* the effective width of the tile */
  guint         eheight;    /* the effective height of the tile */
  guint         bpp;        /* the bytes per pixel (1, 2, 3 or 4 ) */
  guint         tile_num;   /* the number of this tile within the drawable */
  guint16       ref_count;  /* reference count for the tile */
  guint         dirty : 1;  /* is the tile dirty? has it been modified? */
  guint         shadow: 1;  /* is this a shadow tile */
  guchar       *data;       /* the pixel data for the tile */
  GimpDrawable *drawable;   /* the drawable this tile came from */
} GimpTile;