Building images have a previously-unknown flag, 0x0800. The images have
a part that looks like a shadow, but it does not have any palette entry.
I suspect that this flag is related to that shadow.
#include "image.h"
#define FLAG_OVERWRITE 0x0400 /* Draw each frame on a clean slate (unsure). */
+#define FLAG_BUILDING 0x0800 /* Buildings have this, related to shadow? */
#define FLAG_PALETTE 0x1000 /* Image contains embedded palette. */
#define FLAG_LOOPING 0x2000 /* Loop over all frames in the image (unsure). */
-#define FLAG_ALL (FLAG_OVERWRITE|FLAG_PALETTE|FLAG_LOOPING)
+
+#define FLAG_ALL (FLAG_OVERWRITE|FLAG_BUILDING|FLAG_PALETTE|FLAG_LOOPING)
#define HDR_LEN 12