+blitter *blitter_new(int w, int h);
+void blitter_free(blitter *bl);
+/* save puts the portion of the current display with top-left corner
+ * (x,y) to the blitter. load puts it back again to the specified
+ * coords, or else wherever it was saved from
+ * (if x = y = BLITTER_FROMSAVED). */
+void blitter_save(frontend *fe, blitter *bl, int x, int y);
+#define BLITTER_FROMSAVED (-1)
+void blitter_load(frontend *fe, blitter *bl, int x, int y);
+