Document undefined sprite template behavior

gflib/sprite.h

@@ -182,6 +182,10 @@ struct SpriteTemplate
     SpriteCallback callback;
 };
 
+// UB: template pointer is often used to point to temporary storage,
+// then later dereferenced after being freed. Usually this won't
+// be visible in-game, but this is (part of) what causes the item
+// icon palette to flicker when changing items in the bag.
 struct Sprite
 {
     /*0x00*/ struct OamData oam;